What I've Done
The assets for the Chinese officer's sword featured in Fallout 3 were included in New Vegas, too, but they were only used for a static object hanging on Elder McNamara's wall. I simply applied them to a weapon, with stats directly comparable to the katana added by Gun Runners' Arsenal, being slightly weaker but with slightly higher critical damage and slightly faster speed.
The unique variant has a custom texture and its stats are similarly on par with the GRA katana with all weapon mods attached.
Both variants have a special attack in VATS that becomes available at Melee Weapons 50, as usual: the regular sword's special attack is a quick slice for less damage, while the unique's hits really hard but takes more time.
Both common and unique variants can be repaired with the non-unique swords and with whetstones.
Where to Get Them
The regular swords are added to leveled lists for most raiders, vendors and random loot containers. Not the Legion, though, that particular bunch of buffoons are too obsessed with their wannabe Roman cosplay.
The unique weapon... well, in the spirit of Rewarding Exploring, one of my favorite immersion enhancers, let's say that this souvenir of the American counteroffensive into mainland China now resides with the memory of the fallen heroes of that campaign. If that's not enough - SPOILER! - the very first image contains a very unsubtle pointer. :)
(BTW, if you really want the regular variant and can't find it for sale or loot, you just might be able to pixelbitch a couple of them through the bars in that same place.)
Installation
Download and install with NMM! Or download manually, extract into your Data folder and activate ChineseSwords.esp in the launcher.
No DLC or other mods required.
Might conflict with mods that significantly change the unique sword's location.