You can't wait for Dota 2 to come out? Me neither, so get a taste of what's to come with my rendition of the Diffusal Blade. The Engineer recently got a weapon that allows him to reduce a Medic's Übercharge or the Spy's cloak meter. In the same fashion in Dota, this blades burns the victim's mana, and can disable all his buffs, as well as slowing him a lot.
Since this weapon is a must have for Rikimaru, it could have been a weapon replacement for the Spy (both are stealthy assassins) but the size was more similar to the Sniper's knife to I opted for the second choice. It could have been a good replacement for the Demoman's Persian Persuader as well I guess.
Enjoy this Dota in your TF2!