For one thing, you shouldn't try to double weave Fleche and Contre Sixte. The animation lock slows down your global cooldown, and that's never good.

I personally don't take Swiftcast at all on my red mage. I take Lucid Dreaming, Diversion, Apocatastasis, Addle and either Mana Shift or Erase depending on the fight. Dualcast is more than enough.

I also only really use Corps-a-corps and Displacement for positioning. The main idea is you get in close (sometimes early to avoid mechanics), use your melee combo and Displacement to both get away and dodge. In Deltascape V1.0 (Savage), though, you want to be really careful with Displacement. You could go flying right off the edge and die.

Manafication is mostly to add another melee burst, which includes Corps-a-corps and Displacement. You don't use it primarily for the recast reset, but for the mana doubling.

I hope these tips help!