square enix loves ruining things eh? they could have just kept the odin weakness is lightning. then again there is that thing with seifer or whatever.
I see it more as reinterpretation.
Sleipnir and Odin being the same summon makes sense to me. It being lightning elemental makes less sense, but it does fit a very vague norse theme being a reference to Thor. I personally love seeing myths re-imagined.