User blog comment:B214/Question and Answers 6/@comment-185.112.105.215-20161019113453/@comment-10330822-20161021112145

Yeah, Vasco Strada can infuse his fists with holy power to punch devils if he doesn't have a sword. The Holy Swords have their own damage, so holy beings infusing their holy power with the swords increases their overall damage. That is also why exorcists and angels favor holy weapons, because it maximizes damage.

Also, technically the light arrows and holy lightning things are holy power without weapons, they manifest these out of holy power just like Rias does with her Power of Destruction using her demonic power. It doesn't matter if an Angel is fallen or not, they can still use holy power. The only catch is that it seems they are not as strong.