I was looking at the arm/hands items and didn't seem to see any sword / weapon-like items besides a mace and an axe. There are a few different ways a sword can go. 1: A katana sword and sheath. The sword in one hand and sheath on your hip. Colors can change the handle of the sword and the color of the sheath. 2: A neon sword. Maybe glows and paint changes the color of the glow, not the whole sword itself self if possible. 3: A Lightsaber. Same as the neon sword, the paint would change the glow of the sword. Not the whole thing.
This is mostly intentional; the mace/axe are more recent additions as they don't look like usable weapons, but we want to avoid anything that looks like an actual knife you can use/swing, so as to not give impression there's !knives in the game. Same reason we don't have gun props outside of on your back. This works 2-fold, in that those looking for a knife-free server aren't put off by seeing lots of melee weapons, and it helps stop the torrent of !knife spam if they see 1 player holding one. I think if they're straight up swords can probably get away with it, looks like there's a few in TF2 worth exploring; https://wiki.teamfortress.com/wiki/Sword
That sword looks nice too. But I see your reasoning. Okay, what about a sheath then? Would that be do-able?
Sheath is likely fine, we could probably get away with oversized swords (e.g. scimitars) but what Kaiden said is otherwise bang on the money.