Has he ever been tried on the 4th line as a winger?
It seems like becoming an F/D would be a good career move for him. Enforcers are still valuable, but so few of them can play at an NHL level. It would be a lot easier to manage his play if he were a winger than a D. He isn't good enough as a defenseman to play in the NHL, but his physicality and fighting makes him valuable.
Look at Ryan Reaves contract history. No other 10 points forward is getting term and 1-way money above six figures, but Reaves gets it because up until last year or so he was an enforcer who could skate on the NHL.
Xhekaj is not an enforcer, he's got good nhl talent.
He's got great size (6'4 240 lbs), is a good skater (regardless of size), got decent offensive abilities (has an extremely hard shot, good hands + passing ability) and is very mean + physical.
He's also only 23 years old, so he still has a lot of development left. The habs have Guhle and Hutson on the left side, so he's unlikely to play much in the top 4, but he's got the talent to become a 2nd pairing dman.