Ever wonder why he had so much knowloedge of it?

possibly he is keyblade wielder or he has met one before. It is also possible he knows about legend of keyblade war, since he fears keyblade and keyhole.

He was the king of that world keyblade legend was often spread throughout the worlds but only important people knew of them.

cause of this:

Just something that makes me wonder

 

cause of this:

 

i love this

I think he had some bad experience with it myself but we probably won't ever know why

I like devereauxr's reason, but most likely I say we might never know why he knows so much about the keyblade because it's not really important & doesn't contribute to the overall story of Kingdom hearts. My reason as to why king triton knows so much about the Keyblade is because Nomura wanted him to know that much about it.

tutti frutti. Here are some of my guesses. I would think that the knowledge of the Keyblade, and the Keyblade War, from the precessors of the Atlantian Royal Family would have been passed down. That or King Triton experienced something tragic, like MX unlocking the Keyhole and bringing heartless into the world. Whatever the case, it would have been something that had given King Triton such a negative and bleak outlook on Keyblade Wielders in general, since he was so against Sora finding the Keyhole.