Even though just hitting someone with a weapon is quite effective a templar with the right conviction can summon all his strength, all his dexterity and all his faith to unleash an even more powerful blow than any normal warrior could. In order for a templar to be able to use all this energy and actually be able to focus it and put it to use he needs to know that doing it is a good deed. He also needs to be wielding a weapon that is capable of channeling holy energy.