I couldn't find any weapon swaps that worked for me, so I did a conversion.
Old swords are these horrible hooked kopesh looking things. I understand that these are from the masochistic self destructive 3edgy5me faction, but their line troops wield katana looking swords. These are sorta riffing off the yamabushi, ascetic warrior monks, so an appropriate weapon seems fair.
Took plasticard and cut it up, filed the sides down to make an 'edge' and made a ~1mm wide 'tang' peg at the bottom. Lopped off the existing blades, pin vise drilled a hole for the peg, and with some sanding eventually got them to fit.
First model with his fancy new sword
Not sure if I'm going to give it a proper disk/square tsuba or not yet, as they do already tend to have a handguard of sorts in place. Might be the next thing to go away.