He may well have a wrist injury, but the injury might not be that severe that he can't hold a pen or a bit of fabric, both of which are really weighty items that could seriously worsen an injury, especially given that most football scarves weigh about 20kg's and the average pen is about 10kg's, insert mild sarcasm here.
Mellon didn't say what kind of injury but I doubt he was eluding to a broken one.
This is the kind of pen Hughes must clearly not have used to sign the contract, as it could have aggravated a preexisting injury.
Then I ate his Liver.......... with some baked beans and a can of coke.