Things I wish I saw more of in living weapon whumpees: a non-comprehensive list from being around actual Marines and army people
They can and will sleep anywhere... except an actual bed. The moment you give them access to an actual bed with a mattress and sheets, their immediate instinct is to make it up in barracks style, not sleep in it. The moment they're expected to sit and wait and/or have no expectations of them, they lean back and enter a light doze.
Caffeine addiction. Usually through pills, sometimes through special caffeinated gum. This pairs with the weird sleeping habits.
When they ARE guaranteed eight hours of rest, at least two of them are spent maintaining equipment/ their uniform if permitted. When they wake, they're up and ready for whatever comes next in under five minutes. This includes making up the bed.
If it's not the bare minimum to keep them functional and armed, they don't have it. This is going to be especially true for LWW's who were raised in the lifestyle and/or brainwashed after abduction from civilian life. Watches, jewellery, spare clothes, even non-obtrusive things to occupy them outside of training like books or a phone are not things they have without stealing or being given a gift by someone around them.
Paired with above, they have no preferences for what they do get. If someone above them fucks up and gives them too-small or too-large clothes, they just make it work and take the punishment they don't deserve at inspection time. If the only toilet is a bucket on the floor, they use it without complaint.
Their language when speaking freely is something the fuck else, like for real the shit that comes out of their pieholes is unbelievable! A "fuck" every other word!
They only speak when spoken to, and when they do, it's in what I like to call a Sir Sandwich: "Sir, [response goes here], Sir", usually in a very flat and (if appropriate) loud tone. "Sir" can be considered gender-neutral in this case and is meant to denote someone in authority, not a masculine someone specifically.
Buzzed hair on men, pixie or chin-length bob on women, though if your LWW is the only woman in a mostly masc environment, buzzing her hair can be a deliberate tactic by her captors/superiors to dehumanize her.
Food aggression. They inhale their food, they never eat anything that takes time or effort to prepare OR to consume (salad, omelette, pancakes/waffles, steak, etc.) and if the situation calls for it they can and will eat with their hands no matter how nasty their hands are. Permission to sit down for more than ten minutes and actually TASTE what they eat should be alien to them during recovery/leave if they get it.
Hazing. Sorry, but if your LWW is in a group with other soldiers or LWs, they're going to experience some kind of unpleasant/humiliating/dangerous initiation ritual, ESPECIALLY if the team is going someplace dangerous or going to be together for long stretches of time. Stealing clothes while your whumpee is in the shower, mocking them for things they can't control/weren't aware were 'weird', anything and everything that would get them screamed at or punished by the commanding figure on an individual basis. (For my NSFWhump peeps, yes this can include SA or harassment and often does, especially for women and effette/less masculine/nerdy men.)
Exercise as punishment. This can be extra labour, a pointless task they can later be yelled at for not stopping by curfew after not being told to stop at a given time, or even just the classic "drop and give me twenty!". Hitting or otherwise physically abusing a trainee is a federal offense, but for a LWW it depends... are you leaving a mark? Can they still perform as intended?
Just. The irl army is already pretty horrible and I don't see anyone making use of that.