Shadow's Edge vs quest

Hi,
my brother bought Shadow's Edge on the store a year ago to his warrior, but now he realised he can't do the Shadowmourne questline. So if he'll delete the Shadow's Edge than can he pick up the quest and do the line from the beggining?

Thank you all for attention.

Your brother might not have reputation to start this quest, because i know several people who bought SM and did quest line for it. And well, he can always start new character, since you can not dual wield it due to "unique".