Do creature feats like Angelic Weapons apply to any weapon used by the creature?

The example that comes to my mind is the planetar. It does a massive amount of damage for a CR16 creature. I was wondering, if you gave an adamantine greatsword to the planetar (which deals critical hits to objects), what would happen if it struck an object?

My worry is whether or not the Angelic Weapons bonus applies only to some magical divine sword carried by the planetar, or if it’s applied to any weapons used by the angel.

Normally it does 4d6+5d8+7 per single attack (not counting multi—attack). With an adamantine greatsword (which I’m guessing I can’t say it’s conjured with), would it do 8d6+10d8+7 damage to the object?

I want to use this for a wizard, who would Shapechange into a planetar, equip an adamantine greatsword, then attack some boats (by Ghosts of Saltmarsh standards, it could destroy most boats in two turns).

Here is the description for the ability:

Angelic Weapons: The planetar’s weapon attacks are magical. When the planetar hits with any weapon, the weapon deals an extra 5d8 radiant damage (included in the attack).