what's your asset and flaw? if you've got something that doesn't directly hinder magic use sage (if you do do this ignis is probably your best skill since stuff in Apo doesn't have that much RES and neither does anything else) also I know you don't want to but -seriously- consider changing lethality,the only things you'd want to use it on (and I can't even think of one of those because braves pretty much murder everything anyway).
basically,magic asset wants to use this:
Limit Breaker,Vantage,Ignis,Tomefaire, and a filler (Rally Spectrum/Pass/Aggressor/breakers)
in a Lead slot, with a bunch of Celica's Gales and Rescues
while a physically orientated one would use:
Limit Breaker,Axefaire,Aggressor,Luna,Dual Guard+
and be in a support slot with Brave Axes only
basically these are the "optimal" builds,there's a bunch of other things you can use but astra is pretty much < luna/ignis in all situations and Lethality sucks wrt procskills