Kingdom Hearts 2 Sephiroth Ouchy

So I said in my last blog post I'm trying to finish the end of Kingdom Hearts 2 and I managed  to get to level 50 so far.  I also stated that i wanted to get sephiroth's keyblade, I though level 50 would be enough, but i was killed in probably around 5 hits so i have decided to grind to level 60 and try and beat him, but  Is there anything else I should be doing?