@ Wonder
for reference, this is a cutscene depicting what happens when someone grabs the Monado haphazardly by the handle...though it won't always do what is depicted.
http://www.youtube.com/watch?v=PwuLUmWoewkAnd visions like what you're thinking, are fragmented and are so out of context that they don't really make any sense what-so-ever. The vision in the cutscene illustrates what I mean. (The voices did not tie to the scene depicted.)
When used as a weapon, it will slowly injure/ kill the wielder if they can't control it properly.
http://www.youtube.com/watch?v=mQSEdyCG-UkAnd most visions are short term like what is depicted in the last scene.
@ Kristia
ye talking about the "doppelganger" concept with the dark mirror?