On a more relevant note:

Could a Master Class include skills similar to a combat engineer?  For example, deploying special terrain features that boost magic, defense, evasion.  Or perhaps, having a smaller version of an artillery crossbow that can be deployed and fired at targets outside normal archer range. (Deploy-able Artillery would have a shot limit.)

Furthermore, there could be several versions of this combat support specialist.

Heavy Armor: Able to deploy either a small artillery crossbow or a small catapult (chosen before battle during camp phase)

Cavalry: Able to deploy two small artillery crossbows but suffers reduced movement until both are deployed. (canto disabled until then as well)

Flying (Pegasus): Able to deploy two single stat augmentation 'glyphs' by driving their pointy end into the ground.  (Affects anyone standing in that spot.)

Flying (Wyvern): Able to deploy three single stat augmentation 'glyphs' by driving their pointy end into the ground. (Affects anyone standing in that spot.)

Common Infantry: Able to deploy one single stat augmentation 'glyph' by driving its pointy end into the ground. (Affects anyone standing in that spot.)