Link's Hat: unlimited extradimensional space plus the ability to instantly draw and wield anything inside it, including all kinds of armor suits. The capacity to pause reality and think about the best course of action is always a plus.
A mystical artifact that only champions of Creation or equivalent light-bringing cliché'd characters might wield, possibly something that chooses its wielder (it's such a clichè that it appears in a bajillion different operas). Just to make sure that I am a main character on the right side (which is usually the winning side). If it has awesome powers, well, that's a plus.
A Keyblade. Awesome weapon with a thousand uses that Sora never thinks of, and as a plus it allows the wielder to use magics.