As far as I am aware this function is to detect if the player hits xxxx with a certain weapon and not the way round you are doing it.
I thought the same thing when I saw this thread, but not according to the uesp wiki...
For example, player->HitOnMe, "chitin dagger" will return 1 if the player is hit by a chitin dagger.
Here's the http://www.uesp.net/wiki/Tes3Mod:HitOnMe .