- Thanos must have attacked Nidavellir very recently, or Heimdall would have seen and mentioned it.
- So that means that Stormbreaker probably was commissioned recently, since Thanos interrupted its making when it was halfway done.
- Loki has been king of Asgard for the last four years.
From all of this I deduce that Loki, as “Odin”, commissioned Stormbreaker. And since an axe is not the sort of weapon he likes to use, he probably meant for Thor to have it.