When I think of my ideal Mystic Knight, Sora does come to mind. Another that I envision would be Milla Maxwell of the Tales of Xillia games: being the embodiment of the God Maxwell, she used all four elements in conjunction with her swordplay.

Interestingly she, much like Red Mage, has a spellcasting system where she can hardcast or quickcast a spell; difference being the spell had different effects based on hard or quick cast. Hardcasting a wind spell generated a hurricane, and quickcasting it generated three successive strikes of a wind blade.