Question to the DM: How would one go about gaining something like the cursed berserker weapon on purpose?
My idea is to spend the time and gold to have someone enchant his mace with rage 3 times a day. That would require a minimum of a 5th level bard with rage spell and the craft arms and armor feat for a 5th level caster using a 2nd level spell. OR else a scroll for a 3rd level bard of a 2nd level bard spell which would cost 150 and then find a bard with craft arms and armor.
The other idea was for him to get in a fight with his fathers spirit as he levels up to unlock the magic within the weapon itself as it is already a haunted item to begin with. Perhaps for a time he can not control the rage and his father is simply casting the spell on him without his consent in the start of battle and Sinder has to come to terms with his own savage nature, not just his unresolved anger issues his dad is exploiting.