Here's a theory: all celestial creatures in OOTS have halos (and all fiendish creatures have horns, except possibly for those roaches but it's hard to tell at this resolution) That means that neither Windstriker nor Argent nor Razor are celestial. Maybe?
Aside from that, I believe that this strip indicates that Miko has the power attack feat. She specifically attempts to "attack with more power"; I don't think that rules-wise that is possible in any other fashion.