Surely, this card won't be a treasure in Arena gamemode. It won't be a treasure in any gamemode, it is horrible. It COULD be playable at 3 mana and give classes like Hunter access to unoptimal card draw that requires card combos, but at 4 mana it's just horrible.
Pretty bad. Only way I could see this being played is a combo deck with deathrattle activators, that could help go through your deck pretty fast. Thinking of Malygos OTK Deathrattle Rogue with Necrium Vial and the weapon.