An Optimus Prime looking skin.
When he casts Titan's Wrath (his shield) he goes through a little bit of a transformation that raises his face guard and other shield-like components. Another idea is that he expands his chest, revealing an energon core that gives off an aura.
His weapon can be a glowing red-orange axe or sword that is an extension of his arm, rather than him holding it (if possible).
This is a bit more far fetched but when he uses his ultimate, he deploys a smaller autobot (or maybe even a group of them) to chase down his opponents and send them flying.
When he recalls, he transforms into a truck and drives diagonally downward into a tunnel that appears beneath him. OR he turns into a plane/jet/rocket and flies away.