I would recommend leaving GT alone since you've already got access to two skills that rely heavily on AP for damage: power blow (with Ti Wrist if you get it) and Card fling.
Shield All doesn't give that much of a DP boost, but it might be handy later if you go hybrid in job3 (with team bolster and siren song). You might consider getting 10/Master mana reflect anyway, though, because, as Aura writes, monsters will start casting magic at you at some point.
Power blow + Ti Wrist if you want it and Card Fling should get you through job2 okay.
Temp inactive again...
GigaBowser, 4411 HP melee dark/fire/lightning wizard, 193/204
Deudalephon, 4411 3:1::LK:WT melee water/lightning soul master, 150/165
Hemathion, 4411 3:5:4::WT:HP:MA melee dark lord, 140/140
Anchors, 1414 MA priest, 244/250
Vadise, 1414 MA wind/earth soul master, 210/216
IreneAdler, 1414 MA fire/lightning soul master, 154/152
So, like, let's go look for the road and talk about our hair!