Archibald's reference/concept art! Also included is the drawing of Kamsell referenced in Ikushima's note. Translation notes under the cut.
The note that says, "Sad✅" is one I feel really unsure about, in part because the handwriting and angling makes the middle character a little hard to make identify, and in part because there's just not really a lot of context to go off of. I ended up saying that it was a phonetic spelling in Japanese for the Chinese synonym of 鬱 (you can see this particular spelling listed as the "On" pronunciation), because all the other more obvious options (mainly the word "cow" or a word that meant something like, "ulp! [nervous exclamation]," didn't really make sense. That said, I don't think that sort of spelling is used very often (or even possibly at all), so there's a pretty decent chance I just misunderstood that one.
Related to that, I'm kind of going with the theory that since "Sad✅" definitely reads like a joke in English, that might have also been the intention in Japanese. That could explain the unusual spelling, the same way we might write something like, "I guess you could say it has a certain jen ay say kwah" and phonetically spell/misspell "je ne sais quoi" for comedic effect.
And as far as the checkmark goes, that came from the circle symbol at the end of the original Japanese caption. From what I can tell, circles can represent a few different things in Japanese: they can reference the actual word "circle"; they can mean something like a blank (e.g., it happened in the year 20XX, but where English puts Xs, Japanese puts Os); or they can mean "correct" in the same way a checkmark does in English. Circles are also sometimes shorthand for ロ, so it might have meant something related to that as well. I ended up going with the idea that it was a checkmark.
The "God of War" note was a little hard to make out for some reason, and I feel a little unsure of the exact meaning--mostly, I'm not sure whether they were saying that the God of War was Archibald/Kamsell, or whether it's more the person/bear that they're sitting on top of. I ended up just leaving it kind of vague, but there's probably some nuance I missed there. If I learn more when I translate the Kamsell page, I'll make an edit here.
"Strong brow and eyes" might also be translated as "prominent and intense brow and eyes." I used "strong" because it felt like a more natural way to express that concept in English, but I feel like it loses a little nuance in the process.
As an interesting note, "Archibald" in Japanese is something more like "Arch bolt," so there's a little bit of wordplay going on with it.
The first batch of the Seven Saints: Idore and Kamsell! Translation notes under the cut.
The word for "God of War" is almost always used in quotes or parentheses or otherwise set apart. In dictionaries, it seems to just be a common noun, but in this usage, it seems more like a proper one. I kinda wonder whether it might be a reference to a work of literature or Japanese history, but I had a hard time finding anything on it.
For the caption on the first page, I feel like the jack-of-all-trades description didn't really make a ton of sense, and I kinda have the feeling it might have meant something more like "Kamsell was once a god of war and has now become a jack-of-all-trades character instead." However, to the best of my knowledge, it really was saying that the God of War was the jack-of-all-trades character. Related to the above note, I wonder if there's some connotation I'm missing here.