Phase Metal is a material that is functionally similar to steel but can pass through its user (a single person bound to the metal when it is forged into a new form.) as if it didn't exist. Phase metal interacts with all other things normally.
If a person holds a phase weapon that is attuned to them, they must hold it by part of the weapon not made of phase metal. The metal still has weight for its user. The handles of Phase Metal tools and weapons tend to be of wood or other non-phase metal materials so that they can be held by their user at all.
A phase weapon can only be distinguished from ordinary steel if it comes in contact with its user and passes through. Phase weapons interact with armor and clothing normally; a phase metal hammer used against its owner would still deal some amount of blunt damage if it struck armor or clothing, but would not deal damage to exposed skin.
What melee weapons would uniquely suited for this metal? What stylistic modifications could be made to a phase metal weapon that would enable it to beat someone using its normal steel equivalent? Is there a best possible melee weapon for this type of metal?