i'm not so sure if the gaurdian can be his keyblade. i mean it's just a theory but how can a keyblade take humanoid form?
to answer ur first question i guess since master xehanorts keyblade is pure darkness it took on a humanoid form.
i mean its like how can xehanorts heartless have a humanoid form when hes a heartless? maybe the same concept
the problem is, XH already left Riku before kh2 right? only XH's darkness was left which allowed riku to look like him.
not necessarily.
xehanorts heartless darkness is basically his own heart since u know hes a heartless. thats why he said
"my dark shadow will rise someday"
since riku basically owned him there was nothing left of xehanorts heartless but gave him his darkness but when xehanorts heartless gave him his darkness basically riku is using a part of xehanorts heart as well
if thoughts of home allowed riku to wield it, i still can't understand how MX was connected to it, even if destiny island was his home. the way aqua obtained was just thoughts on kairi.
when aqua obtained it from kairi that was probably symbolic jst showing us kairi's connection with destiny islands that she'll have in the future. it's like that pendant. also a conenction with destiny islands that will happen in the future.
and well on mx connected to destiny place that was just a guess. he was raised and it is his original homeland but i like the riku having memories of destiny islands forming into a keyblade and then xehanort "allowing" it is a better idea
2.are we even sure it takes two hearts to dual wield?
not quite
but remember what nomura said? roxas can duel wield but so can sora
without the drive forms. this tells me something right here. it was obvious from the start that sora had vens heart within him once nomura said sora can duel wield withot the drive form.
maybe if 1 heart = a keyblade
2 hearts = 2 keyblades at the same time...
another good example is 'terranort'.
he had master xehanorts heart and terras heart inside him and he used 2 keyblades. not at the same time but he used 2 keyblades. he used terras and master xehanorts