Because he does more damage with one-handed melee attacks than he does using two hands, I assume he has the Dueling fighting style, though I don't see it spelled out anywhere. Also, I don't see Mac an Luinn in the writeup, but I see elsewhere that it's his sword. Maybe the references are there...
Does "so long as an attack or spell is not within reach of his new location" mean the attack or spell that did the damage or is it ANY attack or spell?
If the former, I think it should be specifically stated. If the latter, I can't imagine the party not having some ranged attack or spell that...