I know how this looks because I'm the most biased person on earth not just because I prefer Eridan but because I also vitriolically, bottom of my heart, with every fiber of my being, hate Feferi Peixes... I low key don't see it. It made me rethink something and even investigate some things as symbols I previously hadn't but idk I still think Eridan was reacting to being attacked, justifiably so or not (and while I'm #1 Eridan stan and #1 Feferi hater, Feferi was fairly justified).
But okay, first point. I'll be honest this first one I really don't get because the order of panels is not indicating one way or another whether that what Feferi turns to see having happened or what she turns around to see happen.
Paying attention strictly to the order of events, it's important to consider how much the scene is referencing showdown, quick draw, duel scenes of westerns. So, Eridan's wand glowing at her side can be construed as either doing that thing where the outlaw unlatches their holster in preparation for a quickdraw, or cocking the hammer of a double action revolver to make it a lighter trigger (I lean towards the second, it's the one that most closely analogizes to the wand "charging up" as you put it). In either case, that panel of glowing wand indicates provocative, even escalatory preparation but still not action. Readying to react, rather than triggering the duel's "start." Compare it with panels of Eridan vs Kanaya. The standoff begins, with both weapons being in a wielded but not fully ready state. Eridan picks a target and while Kanaya shows hesitation, Eridan charges it up/cocks the hammer so that what she does next can be done quick as possible and giving the most leeway in responding to how Kanaya will react. Hopesplodes the matriorb, instantly provoking Kanaya, at which point there is no point to cocking the hammer in advance and Eridan extends her hand, aims, and does the equivalent of shooting with the trigger completing the double action all at once.
Keeping that in mind, we can just as easily boil a larger sequence of panels to being fast paced or slow paced to be charitable to Eridan again.
3326. Feferi standing over a hurt sollux. No evidence of wand being charged up
3327-3329 all happen in such quick succession we can view them as in one fluid motion. Since on page 3326 Eridan hadn't charged up yet, we can say she charges the wand as Feferi turns around, we can also say Feferi charges in the same motion of turning around.
The implied motion of this fast pace can be just as charitable.
Interpreting the panels as slow paced;
3326. Feferi stands over Sollux, Eridan again in the background idle.
3327. This time while she turns, bares teeth in aggression, and begins brandishing the trident, it's not implying motion of her going into the leap right away
3328. Eridan still hasn't raised the wand fully, keeping it charged/cocked, but pointed downwards into the ground
3329. Feferi doesn't just charge but leaps, almost cementing it as a point of no return since there is no stopping a leap, the momentum will carry you to your destination until an counteracting force acts upon you
3330. Eridan glares. Now that the duel is started, it makes sense for even a slow pace to have picked up by now to not make it overly charitable by implying hesitation. Eridan still has a slight moment to react to the news before...
3332. Imperial light destroys the Heart of Darkness. Ms fef, she...
In the slower paced interpretation, the panels tell the story of Eridan determining to fire once it focuses on her look, after Feferi has leaped. So I can't be convinced much by suggesting interpretive pacing of actions in the panels.
Okay, so to second point about Feferi's ability to cause harm with her weapon. Let's ignore the fact that it's kinda slightly moving the goalposts set out in the title a bit from "if she attacks" to "if she attacks but Eridan should be able to determine how lethal a trident stabbing her would be, where Feferi is planning to attack from across the room, how lethal that area is to attack, and then and only then counterattack proportionally to her best estimate of perceivable threat all while said threat is leaping at her with a trident." I want to call it a rhetorical sleight of hand pretty well employed. I nearly went on having missed it and just engaging with the change. Whatever though it's still a valid question even if I had preferred it be the original consideration so to not imply the title's question was the overarching question. Maybe it didn't make the cut for being a mouthful. Well okay, Eridan is doubtless more effective at killing than Feferi. That's not really in dispute. Between a lifetime of orphaning as a job, FLARPing as a hobby, a month playing Sgrub on LOWAA on hard mode, and at least one test of her new weapon on Sollux, any action Eridan is free to take can be made to be absolutely unambiguously fatal to anybody that is not directly beam struggle troping her.
I initially made a power scaling esque argument here but while it's dumb fun to make, I also think less relevant than looking at what happens later with Kanaya as a rainbow drinker. Sure the transformation probably makes her stronger but it mainly shows that Eridan's threat is contingent entirely on distance. Kanaya's being fast and angry as shit is Eridan's weakness, not necessarily her strength. Kanaya very easily disarms Eridan once in that melee range, at which point Eridan poses no resistance, and is easily cut in half (R.I.T.P.).
Alright so could have Eridan given Feferi benefit of the doubt and assumed that the person charging at her with a trident was doing so with non-lethal intent like stabbing a leg to incapacitate. I guess if she felt like she could still trust Feferi but I think if we're going with Sollux looking like he might've died from that, Feferi's angered face and the gold highlights in the panel definitely reads more as revenge motivated and thus probably lethal intent. Even if we figure as Life aspect Feferi is tuned into it being a K'O, to Eridan's perspective the difference between incapacitation and killing doesn't matter. Stopping her from leaving the place she has no hope of living in and killing her on the spot is essentially the same result. Ironically it's kinda just a matter of getting one's hands personally dirty which would actually fit great with the themes of Feferi and Eridan but I digress.
But onto the trident being ceremonial. At the end of the day it's still a weapon with sharp points enough to stab through flesh. They're not exactly the angels of LOWAA but the brains of LOFAB were still fleshish. Stabbing them killed them. Kanaya used the same lipstick chainsaw she started Sgrub with to kill Eridan, upgrading their weapons for lethality only seemed to be necessary for game constructs with HP totals. The players all seem to keep relatively mundane vulnerability to grievous injury sans Gamzee. Equius' ridonkulous strength didn't cause an arrow to bounce off like it's a video game, it went straight through his leg and if it had been pointed at his heart he would've died.
And to just argue the case of Eridan only pulled the trigger when attacked consider this: Eridan's whole aim at that moment was to preserve any chance she had with Feferi. Even with the most Eridan-critical lens of creepy obsessional love it would make the most sense for Eridan to only kill when her chances are provably zero by the fact that Feferi is mid-attack. Devil's advocate: was her mind made up at the point of verbal rejection? Archangel esquire: then surely Eridan would've been "charging" up in a sooner panel than when Feferi bares her teeth and brandishes her trident. Besides Eridan has already been rejected by Vriska, Kanaya (somewhat repeatedly), Feferi, Feferi kinda twice, Equius (repeatedly), Nepeta (repeatedly), Karkat (somewhat repeatedly) Terezi (implicitly more than once), Sollux, Rose, Jade (repeatedly), and Feferi again by that point. Sorry if missed somebody or a repeatedly qualifier in there somewhere; I'm pretty sure Sollux and Rose too but I'm not gonna bother checking the exact pesterlogs. The most violent Eridan's been towards a rejector is presumably her duel with Sollux but since that's for pitch romance I don't know how to count it, so I'll also bring up that she straight up iced Johnnytop when kinda rejected by Jade (the most unforgivable murder Eridan commits, since Johnny 5 is a sentient being and likable in my memories of Short Circuit though I fear returning to the movie and realizing how annoying he is as an adult). The point being, Eridan gets rejected often but doesn't quit until it's pretty clear her chances are zero. And I think if Feferi was truly her last hope, she'd wait until it was absolutely unambiguous she has no chance, like when Feferi is mid-attack.
Now while I've written a lot to hopefully prove my point just to be as thorough as I possibly can as to why I believe what I believe; I do think a lot of it is just superfluous. I think ultimately the actual answer is that whether or not who attacked who first, their hostility towards each other was decided in advance.
Boiling it down to a very basic level if people A, B, and C are arguing, and A and B collectively say, "we're going to stop you, person C, even with force if necessary." And person C said "alright, bet." Even if person A (Sollux) takes the lead but they get their shit rocked, the conflict between A and C is already implicitly started, because it's just a continuation of A and B vs C. Hell go the logical extreme, even if Eridan dropped the wand voluntarily, Feferi ran up and knocked her out cold with a right hook nobody in their right mind could call it a sucker punch, Eridan was literally asking for it.
Anyways that's it. Not like I think people are going to really consider anything I said. Everybody knows how this goes, a typical Eridan fan expressing every single bad political idea in the world defending Eridan. Whatever.
