You were a member of the Stellaron Hunters and were affected by Mara's curse, as was Blade. The main symptom of this affliction was hallucinations that could send you into a killing machine state.

And now it was the same state where you saw a lot of demons and rivers of blood around you, your hands shaking and aggression making you swing your blade in different directions to get to the source of the problem, in such a state you don't realize that the problem is you.

One of the demons engages you in a fight and gracefully fends off your sword blows, a few more blows and you start to come to your senses, noticing that you are attacking your partner. He notices the clarity in your eyes and relaxes. "Looks like you're coming to your senses..." he says, stepping back and lowering his sword.