One of the House Redoran quests has you convince Rothis Nethan to fight in a duel in the Arena, even though he clearly cannot win (he onlly has a dagger against an opponent in full bonemold and wielding an enchanted claymore).

So I tried to help him in various ways: casting resore health on him, casting fortify skills/attribute, etc. I even tried to cast Bound Long Blade on him but apparently it doesn't work as a "On Target" spell.

So, has anyone tried this, and succeed, and if so, how ?