Weak lore implications of Obligator

I'm really struggling to rationalize the lore implications of this Guthixian themed weapon inside the vault of Guthix.

So its a megarare, incredibly powerful item, that the bosses of TFA are protecting but presumably not using?

I was really excited about the possible lore tie-in of the Titanic Breaker being this powerful Blackstone artifact that was being shielded. Even the poop chain made more sense lore-wise.

Happy to hear some other pitches of how or why this Guthixian megarare ended up in the vault. I'm sure Mod Ed could cook up something interesting, but it does feel like by far the least cool of the three as far as lore is concerned.