Yep, it's Use Best Weapon Skill - And the nice thing is that, for some reason, the swatter is acting like a double-slayer (automatic maximum DI) against the fallen warriors.
My paladins, with only Stormgrip for DI, do the same amount of damage with or without Enemy of One to the warriors, with or without the gloves. Somewhere (depending on their resists) between 120 (low-end damage, versus higher-resist warrior) to the high 150s (high-end damage, low-fire-resist target).
Against the wisps, averaging the high 20s to low 30s, normally with the swatter, high 40s with Enemy of One. The downside is that the warriors hit for about 75 points per swing, if you have EoO up against the wisps (or anything else).