I can list off a few
For melee weapons there's swords, a weird whip-like thing, a frickin chainsaw, a baton, and others I can't describe well. (melee can only be put on the left arm. Similar with energy shields which can only go on the left shoulder)
There's tons
For guns there are a bunch of machine guns, standard rifles, handguns, pistols, grenade launchers, missile launchers, and laser guns (think I got all the different types. Everything but melee weapons and shields can be put on both sides)
For shoulder weapons there are four main ones. Missiles, bombs, drones, and shields. As I said with melee weapons, shields can only go on the left