There have been some great responses above, but aside from the aforementioned…
As far as Toa Tools go, I think Varian’s arm blades were pretty cool, especially given that she seemed able to conceal them on demand.
Zamor launchers are also a worthwhile mention when you understand how they actually function in-universe (Glass spheres that intangibly pass through your body before dissipating and unleashing whatever liquid you’ve decided to fill them with prior).
Thornax Launchers are really crazy awesome. Fruit Guns! And you can canonically control how lethal they are depending on the ripeness of the fruit, too!
I’d also like to mention Rhotuka. They’re kind of just boring energy blasts, but what I do think is cool is that these are artificial weapons based on natural ones. Not to mention the really cool canon tidbit that their powers are controlled by the user’s morals and ethics (or lack thereof)! That’s really neat - character insight from how a weapon functions.
And I think the Spear of Fusion is somewhat original, though also pretty messed up.
And of course, anything from a weapon contest is going to be good. So naturally pretty much all of the Xian Weapons are worth mentioning. I particularly like the Twilight Blade, Impact Crystal Launcher, and Eccentric Rock.