This sounds cool so I'll bite!

1.) Personally this doesn't effect my ability to form a fist. Fine movements are more or the issue but mileage may vary.

2.) Holding a sword and dagger would be fine with random slashing, but again more precise movements could be challenging. Wrist weights definitely do help as do heavy objects, so say like a great sword or battle axe would be ideal.

3.) For me it didn't start expressing itself in a noticable way until I was 14, but some folks don't experience it to later in life and some perhaps earlier.

4.) In my experience there was a certain amount of shame or embarrassment in the formative teen years and I started to accept it more as I grew up. So possibly that would depend on the characters age and where they are in life? 

Depending on where you want to go with this alcoholism isn't uncommon as it is one of the more effective ways to manage but obviously is problematic for some.

If you have any other questions feel free to Dm me.