DragonShadowWing
left handed see pic
[PIC]
read what it says if you can it will tell you
link
http://i125.photobucket.com/albums/p53/fox-__/officialart8en2.jpg
and for those of you who wont be able to i will tell you what it says
"yazoo, loz, and kadaj are the physical manifestations of sephiroths spirit-yazoo is his allure, loz his strength, and kadaj is his cruelty. kadaj is left handed because sephiroth is left handed"
(nomura)
[PIC]
read what it says if you can it will tell you
link
http://i125.photobucket.com/albums/p53/fox-__/officialart8en2.jpg
and for those of you who wont be able to i will tell you what it says
"yazoo, loz, and kadaj are the physical manifestations of sephiroths spirit-yazoo is his allure, loz his strength, and kadaj is his cruelty. kadaj is left handed because sephiroth is left handed"
(nomura)
Yay, proof!
So apparently, he is left-handed, though I'd say he can probably use his right hand pretty well, too.
EDIT: I don't know where that picture is from, but I also just found out that it specifically states that Sephiroth and Kadaj are left-handed in the Final Fantasy VII Ultimania Omega.
(http://faqs.ign.com/articles/698/698416p1.html)