> ...Katana, Severed Arm, Bloody Axe, ...Master Sword
That's a common theme of most of the suggestions I've seen - violent tools to harm your friends. Not to mention slingshots reshaped as guns/shotguns.
I suspect those will be the most popular items (like lightsabres)

That's an advantage of hacking, you can make items the company can't/won't make.
FWIW: Nintendo won't make these kind of items, since they aren't consistent (ie. you drop it and it is an axe or a slingshot) and not kid friendly.
Also the DLC mechanism isn't that flexible. I don't know if you can do proper animations yet (ie. a real spinning top?)
More research is needed to see what can be done