How about a knife which turns anything it kills into dust
Or a two bladed sword like Darth Maul style for some kind of tempel guard or something, where they dont need to move around a lot and can always have the sword unsheathed cause that seams to be the most annoying part, of cource high roof and a lot of space would probably be necessary to move around properly. Though it would probably need to be some kind of straight blade like european longswords rather then a katana sry
K O B O L D K A T A P U L T ! ! !
A bone necklace which makes one of your eyes glow blue if you play the trombone
Or how about a classic: FIRE SWORD
Or counter point: ICE SWORD
OR counter counter point: ELECTRIC/THUNDER SWORD
OR counter counter counter point: FLOATING SWORD
Or, if none of the rest is any good, how about an entire arena full of 78 kittens all cuddling with ME
I sort of have the principles of "knife that turns people into dust" thing built into a certain sword called the Sakurajimaken, an old battle sword hidden in a protected shrine on a secluded temple island that instead of leaving wounds, leaves sakura trails, instead of blood, Cherry Blossoms shoot from the enemy, and if you cut a limb off, it disentigrates into the bloss. too.
Also, the double-bladed sword did in fact exist and is actually suprisingly practical in some situations, and would be an excellent fit for a temple guard. I could see if i couldnt make a curved version, but Asian history is no stranger to a straightsword.
Also, elemental blades can be really cool.. If done well. I'll be working on some concepts there, too.
Also, to compensate you for your ideas, 78 kittens are being shipped to you RIGHT NOW!!!