First, are you clipping his nails? If not, start right away. Clipped nails will make a big difference. Also, when you see that he wants to come up on the couch, lift him up gently rather than let him claw his way up on his own.
Next. Cover the couch with Waterproof Sheet Protector. And have a towel ready for your lap to soak up pee if what you describe happens again (and again.....).
The couch needs to be protected from accidents otherwise things will reach the point where you'll have to get rid of it.
One other thing. Because the word vicious is loaded with negative meanings, actually there is not one positive thing associated with it, I urge you to change his name and also start using lots and lots of words and nicknames for him that have the opposite meaning, bringing to mind gentle, calm, sweet, etc, etc, etc.
He is a handicapped kitty but he understands words just like any other kitty and he also responds to suggestions that encourage good behavior that does not involve clawing for any reason. Help him when he needs help to prevent clawing and then praise him for what a good baby he is. And use the words gentle and gently as often as you can. Many, many times. He'll understand. He'll learn what it means to be gentle even if he still needs occasional reminders.
I learned from an article many years ago that cats have the vocabulary of a two and a half year old child. They understand a LOT. And they respond to everything, all the words we repeat often. Especially when we keep repeating certain words for a particular reason in a particular situation.
When it comes to behavior our kitties respond to the words, our tone of voice, our facial expression, our body language. Keeping this in mind a lot of love and patience and never any harsh words or reprimands make it easy for us to change problem behaviors for the better. Always remember, repetition is the most important part of teaching kitties what we want them to learn.
I can't help wondering that, from what you describe, peeing after he gets up on the couch might be his way of marking his accomplishment. Maybe, maybe not. I wonder if there might be something to discourage that. Perhaps finding a different material/texture on the sofa by itself could be helpful. Not sure, you would have to find out.