Okay this is getting kind of annoying. I've already killed a mercenary and that cult leader for that daedric quest "Boethiah's Calling" so that should be two (still nothing happened.) Then I delivered some supplies for some guy as a side quest and murdered him in his sleep with the blade. Now what? Do I just keep killing people that trust me? Is it glitched? I really wanna use this sword.

You have to gain somebody's trust enough that they become a follower. At some point they suffer an "industrial accident" and you should see the strength of the blade improve. I got this blade too late in the game to be able to charge it easily. Supposedly you also hear a message about how well you are doing when the blade gets a charge, but I've only heard it once. Seems all rather pointless.

Every second friend you kill using the EB Mephala will speak to you until its fully charged after 10 murders. If you're not getting the message then either they're not friends or its glitched.

edit: The mercenary and the guy you delivered supplies for should've counted as friends, not sure about the cult leader, so Mephala should've spoken to you once. You must kill them using the EB.

Figured it out.. yeah you won't always hear the voice, it's every 2 or 3 kills. You need to kill 10 people who are either followers of you, or that you've helped before with a quest. My only problem is deciding who to kill because I tend to try and stay a "good guy" when I play these games. I managed to find a bunch of sorry sons of ******s though and chopped them up now the blade is fully charged and believe me it's one of the best in the game. It's only 24 damage and i'm level 39 plus 30 life leech and I think it can be upgraded too. The thing about it is the ebony blade benefits from the 2 handed and the 1 handed tree. So it's actually faster than the average 2 hander from what i've seen and it can still decapitate and paralyze. It's a pretty strange but it kicks ass. Well worth the bloodshed.

I got the Ebony blade on one character and it went straight into the chest in my house. I've never touched it since. I just wanted the daedric artifact for the achievement. I would never put a blade above my friends... LOL (well worth the bloodshed LOL)

With a two handed weapon skill at 100 it does 33 damage +30 life absorb. It cant be upgraded. The weapon will keep you alive against Ancient dragons but it'll take a long time to kill them. I fixed this weapon by using the fortify restoration glitch and raising it's damage to 170 which is probobly the damage it would do if you could improve it at a workbench and add a +47% fortify one handed weapon enchantment.

just try to enchant your blade im actually going to do that and im trying 2 get all ebony armor bcuz after finding out that everbody uses daedric amror and i used to wear dragonplate but ebony looks so old fashioned its kewl