I don't think this riddle has anything to do with anything else. It can't be a normal character because characters are dependent on stats, the only character you can find as easily, that's within ruins is yuffie. As Wutai is classed as Wutai Ruins. and no normal character has a master.
It cannot be an ordinary weapon because 1 that is dependant on the characters stats and levels, and they change all the time. The answer needs to be a stict straight forward answer. Besides you can't look at a weapon and say oh this looks stronger than you because you don't see any weapons in great detail besides the Junon canon. And even that cant be it because it was not found in ruins, and it doesn't have a specific master.
It can't be an item because items don't look stronger or hit harder than anyone else. Not to mention there are very rarely a set of items only found in one place.
It's not a materia, it's not a main weapon.
It can't be a place because places can't look stronger than a human being. Rephrase the riddle because it's not literally correct, and makes no sense whatsoever. Unless it's a rhetorical riddle then you've really messed with our time.
