A thing about Medic Staff that might be a bug:
The healing from the healing attack actually gets reduced when allies use the "Defend" skill. Also, i think the Defense (or MDEF) stats also reduce the healing. Wulfrick has the highest Defense and solid MDEF in my party, and he gets less healing than the others. Meanwhile, Fucko has the worst Defense investment and he receives almost double the healing.
I have put a lot of points on Lace's MDEF, and he gets basically no heal.
I don't know if it's intentional, but it looks like a bug.