The Martial Power Source refers to years of studying fighting technique and tactics.
Tapping into the Martial Power Source:
The only way to gain Martial Power is by rigorous training of the body and sharp strengthening of the mind.
Martial Power Source Bonuses
Combat Advantage gives you +3 to the attack roll instead of +2. +4 at 21st Level.
Combat Advantage also gives you +1 to one damage roll every round.