Who knows in what stage of healing the pictures were that you saw?
I would NOT recommend testing for you at all. And if you’ve read my posts, you know I recommend testing very often. But not in this case. Of course if you put alcohol on it you are going to get abnormal patches of skin, alcohol is such a drying agent.
And yes, if you punch things, you are likely to get sore knuckles.
If I thought there was any risk at all for you, I would tell you, I promise.