I would like to see a Thief dw'ing knives. A Corsair or Red Mage (w/e) dw'ing a pistol/rapier combo. If a Ninja class was created (I am not sure it fits the FFXIV "feel" which is arguably less oriental than FFXI) I think one katana as you stated, or Throwing Star/Wakizashi (short Katana) combo similar to the above mentioned Red Mage ranged/melee blend. The Red Mage (or Corsair) pistol and the Ninja throwing stars could be used at range for debuffing/building TP in addition to modest TP, and then melee Weaponskills at close range.