Hi,
it seems that the Fel Sunder Talent (Demonology Skilltree) is permanently active after once speccing into it. Changing talents, spec, restarting the game didn´t fix it. Iam using both, the Wrathguard and weapon transmog Glyph on my Felguard.
regards
Edit: So, entering a dungeon fixes the bug. But you can easiliy reenable it in dungeons or raids by specing in and out of “Fel Sunder” inside. After leaving the dungeon the bug persists.