3rd crystal..so your at/past goldor? If so, switch to dragoon. You get pretty good items (free) at sardonia if you just look for them.

Dark knights would be pretty good, though Im not sure of how they are at this point, but with a blood sword, thier souleater ability pretty much takes away no life.

Vikings, if your looking for job level speed, are teh suxors, but are phenominal with thier gear.

Lastly, Knights! If you cadd two shields to them, they can just be the tanks of the party.

And cant help ya there with your magic problems