I was unable to kill the hard boss for the blackstar weapon questline after sacrificing the eye of desolation at the alter. I was unable to do any other attempts on the boss due to the brazier not giving me an option to sacrifice the eye of desolation again. I quit the quest and upon coming to the crossroad option took the easier killing helms route. I am currently back at the brazier with the weakened version of the eye of desolation and still unable to sacrifice it in order to fight the boss. I"ve forfeit the quest numerous times, re loaded the game, and switcheed servers. Any help? i just want my blackstar weapon!!!!

I have the same problem, do You know how to fix it ?