I would say no... But I have a hard time playing an "evil" character so I never really used it. Although my character has no problem burning bandits to death. Haha, so she's not exactly a priestess either. :p

Its useful only if you 1) dont want to work on your enchanting skill early in game, and 2) want a unlimited charged weapon for your followers (read its wiki page for more info). I basically handed it to one of my Housecarls and had them rip thru enemy ranks while my character sniped all the other baddies.

As for getting it up in power, you may have to kill off townsfolk in small towns, mills, and farms that you befriended (this will take some travel and time, but trust me, there are others who can buy your goods in the big cities) Once again, look to the wiki page for a looooong list of potential victims. At the end of it all, tho, its a good lvl 20-30 weapon for two-handed users until they find a stronger blade, then its better off in the hands of the easily killed followers.

You're supposed to kill 10 NPCs that are friendly towards you, as mentioned above there is a list of potential victims on the wiki page. But there is a better way: if you have the conjuration skill "Dead Thrall" or the Ritual Stone power you can kill then resurrect the same person 10 times and it will count. Best way is to put the ritual stone on the aetherium crown, then all you have to do is equip the crown, kill the person, then unequip and reequip. And repeat

Thanks for the info guys