I haven't actually played XIV for a while, but XIVApp has (had?) an enmity counter that I assumed pulls directly from the game's memory. I'm assuming this because it matched additional enmity from Fracture DoT ticks perfectly (I think I checked with Defiance on and off) and DoTs aren't parsable. Which sort of makes me wonder why we don't estimate DPS with enmity. Or do we?
I did my testing on mobs right outside Revenant's Toll, but basically I got the exact same numbers as Niiro and drew the same conclusion as Seravi ("wait, why would you ever Tomahawk?").
If anyone's curious, on my Paladin and Warrior (same iLevel with basically full Soldiery gear and T5 weapons) I remember Flash was in the mid-600s range per cast and dependent on gear. Paladin Flash was about 50-odd points higher, presumably because of the blind effect attached to it.