So, recently (like 2-3 weeks ago?) Team Fortress 2 got another update with more new weapons to find/craft/buy. It was part of a promotion for some game, such that anyone who pre-ordered that game automatically got the weapons in question for free, guaranteed. (And I think that they might have had nice names or levels or something.) Anyway, there's a bunch of East Asian-style stuff in there, and one's a katana called the Half-Zatoichi. It's a bit like the Pain Train in that it's a melee weapon usable by the Demoman and the Soldier (so far the only pair of classes to share weapons). As always, it's got benefits and drawbacks compared to the standard melee weapons (a shovel for the Soldier, and a rum bottle for the Demoman).
The drawback is that, once it's pulled out, it can't be put away unless and until one gets a kill with it (or one dies, resetting back to the primary weapon). The benefit is that, whenever one gets a kill with it (which makes it bloody, indicating that it can be sheathed), one is restored back to full health. To me, this is kind of meh. Probably one of the things that makes it less than appealing is that, if one sheathes the Half-Zatoichi, then pulls it out again in the same life, the blood's gone and one has to get a kill again to put it away again. It's not terrible on a Demoman equipped with the Chargin' Targe, but it's pretty rough on a Soldier, whose only advantage is his higher health. Equalizer, please!