I was thinking about Deathstroke's healing factor and his eye and all that. It came to question in my mind
 
Has his eye ever been a burden to him? Has it cost him a battle? Anything that he regrets about it?  

 

 During the big fight in Identity Crisis Green Arrow stabbed Slade in his bad eye, causing him to lose his temper which cost him big time, if it weren't for Dr. Light the Justice League may have finally caught him. 

also In Birds of prey #90  Black Canary nearly beat Deathstroke by taking advantage of his blind side and wounded his only remaining one which cost him a job.
 
but most of the time his impairment doesn't effect him at all in combat, most of the time his down fall is his egomania and pride.