Actually I think I came up with a possible idea for that guy, Archer. We have the Arms dealer for guns but there's nothing for bow users but I don't know how nesccesery that would be.
He doesn't looks like an archer, I think...
And, the merchant already sells arrows - which are easy and cheap to craft from wood and stone anyway. other archer ammo are created similarly like other bullets, right? crafted from regular arrows and other stuff.
And bows are crafted easily, or otherwise dropped by bosses.
I see no reason to add a character like that for vanilla items only. it would make some sense, if a mod offers more archer gadgets though.
in comparison, the arms dealer sells only a few stuff too. it's part that you can't craft musket balls, why he's crucial if you're using guns. otherwise he only sells a few things. flintlock pistol is rather useless since you almost all the time would have a musket or undertaker to get him to move in, to begin with (although it could allow for more players to buy guns in multiplayer) then, there's the minishark, which is strong, but it's just one weapon. illegal gun parts that craft a few weapons. and some ammo. he has a rather small shop overall. it's just that those things can't be crafted, why he's important for rangers using guns. He might be there for balance reasons. Plus, he's an overal fun guy to have around, but his shop is rather small.
That aside, I also had some other silly ideas.
Mimic merchant!
(would need to figure out what sort of AI it should have to work though, to be stationary, and also friendly)
So, this would be like skeleton merchant, appearing randomly underground (only in hardmode maybe)
look like a gold chest mimic, so, it could spawn offset and stuff, that tells that it's not an actual gold chest. approach with caution, or you shoot at it from far, but nothing happens, you get closer and click on it to open if it's a chest, only to be greeted by a friendly mimic XD
"Hello there, wanna buy something?"
alternative even with some quotes like "Mimic?! Where?!"
Sounds like it could be funny, and catch players off-guard a bit the first time they encounter it XD
and would make mimics a bit more fun, so you couldn't be that sure whether it's a dangerous one, or a silly odd merchant mimic XD
not sure what would it sell though. treasures that mimics drop...? dunno if there is need of a merchant like this, but it might could be funny, and surprising. XD
(same could work with things like lost girl too, for the same reason, players used to it that the lost girl is actually not a lots girl, but a nymph, so almost no one will be tricked by them by now, or they would fool you only once, and never again. but if there would be an actual lost girl... it could be different.
However the lost girl is a tricky one to work with, because while she is naked in vanilla too, Tmodloader has quite strict rules for stuff (even though there are mods that add things that look like girls naked/half naked?, like those bottled waifus in Calamity? I dunno them much though since I don't usually play calamity.) point being, breaking rules could get the mod deleted, so I'm careful with any content that sounds like could break the rules. that's why lost girls are tricky.
(likewise, a stationary lost girl (like the guards) could have very high and actually funny troll value, if someone put it in the cavern and you have no lifeform analiser yet, to tell you that is just a fake one.
but tinkering with lost girls seems dangerous regarding rules, so I will probably avoid that.
(I did used the lost girl's sprite for the Scam artist though, to begin with. She's not naked though, so she's fine regarding rules about forbidden content for Tmodloader, like nudity)