As the title says it, I have encountered two problems during fights:
1) on random occasions I cannot use my 'stampede' skill despite having plenty of stamina, targeting my enemy properly, and having a clear path in front of me. The ability won't work, and the slot is dark as if inactive for some mysterious reason.
2) when using a power attack, I sometimes get stuck in the middle of the swinging animation (I can still move, but my sword and arms are lifted in some awkward pose). A second power attack would get me unstuck, but it may take a few seconds to do it (especially if I am low on stamina), which obviously is not good in the middle of a fight.