Unarmed Fighting
If you have Improved Unarmed Attack:
add +2 to your unarmed damage
If you aren't wielding a weapon, add +3
At the start of each of the turns, you can deal your unarmed damage to one creature grappled by you.
Why Not Protection and Interception?
A Tyrants occupy 2x2, 3x3 and 4x4. Therefore they can already cover many more squares than a medium sized character. Their increased size already gives them increased coverage.
Note that these fighting styles and similar feats/abilities don't increase distance when used with reach weapons either.