Leaving the arena with unsteady steps, small traces of blood were left on the ground where Desmond had come from, showing that even when he was victorious; he had to pay a price for it.
To be precise, Desmond was able to defeat Zi because Desmond was willing to pay the price. While Zi had always been ruthless towards his enemies, Desmond was willing to go one step ahead and be ruthless towards himself as well.
In this way, Desmond was willing to accept the tremendous backlash caused by the excessive use of <overload > in the same way that he was willing to completely discard any defensive notion to concentrate every ounce of his strength on one single devastating attack.