I imagine that you will suffer the same 'loss' as if you had disconnected intentionally. There is likely no way for the devs to tell the difference, and it would be unfair for the attacker if you were to disconnect either way in the midst of battle and they get nothing for their effort and potential losses.
However: Perhaps there could be a 'waiting' feature. Basically a sort of 'pause' that would enact in the battle when someone disconnects and which gives them a preset amount of time to reconnect. Say - 5 minutes. They get disconnected and have five minutes to reconnect and resume the battle - if they fail to do so then it is a 'loss' just as if they had declined the fight to begin with.
"He uttered the word of curse, crush him with our Orcish iron!"