I recently got the Gauss Rifle and Jingwei's Shocksword, and they aren't in 100% condition. Is there any way or any merchant that can fully repair them? thanks.

Jingwei's Shocksword can be repaired with Chinese Officer Swords. For the Gauss Rifle, the only way to repair it to 100% is to use Alien Epoxy from Mothership Zeta or use Haley in Point Lookout if you've successfully glitched his repair skill to 100.