Yeah, I was thinking of that as well, but UI isn't really a limiting factor since you wouldn't likely have weapons that are capable of every single possible type of attack--instead they have a smaller subset, but the range of the total set can be much larger. For example a sniper rifle that lacks other normal firing modes in favor of two kinds of aimed shots, one slightly quicker and one more careful. That would still only require maybe four actions: Throw, Aimed, Snipe, and Melee (assuming the addition of melee attacks for most weapons).