For the most part, just listen to what Glenn says. I'm not sure about this, though.
The Black Knight can wipe Ike out in 2 or 3 hits, IIRC
Personally, as I always stat-abuse Ike and Mist, they're both 20/20 by the time of the BK fight, and Ike has max Hp, Str, Skl, Spd, Def, and Res. (Thank goodness for RD transfers...)
I have yet to try the good ol' Adept and Wrath combo, as I always use the Miracle+Aether skill set. >_> I'm something of a traditionalist, I guess, because I have never once lost, or never once not had Ike at 20/20 by that point, though I've gotten close to losing my first time...
As long as your Ike is ranging, you need to watch out for that annoying Bishop, whenever he appears. If you can kill him before he heals BK, be sure and do it.
I don't remember: can Ike win (assuming he doesn't miss) without an Aether? if you aren't using Mist and have to Elixir abuse, I don't think you can, but if you're attacking both on your turn and countering on the enemy's turn...
Wish I hadn't loaned my copy to my cousin, who has yet to finish a single video game... T.T
Sorry I couldn't be of much help.