Language. You can speak, read, and write common and celestial.
Arcane Blindsight(15ft). You can't discern color or invisible things. Additionally, you can see and hear through the eyes and ears of your host.
Steel Soul. The weapon's creature type is construct for the purposes of spells and effects. Healing potions and spells don't work, instead mending will heal 1d6 hp. It doesn't need to eat, breathe, or sleep.
Bite the hand. Any time Test would be knocked or dropped from Deric's hand(host or not), they can make a Str or Dex saving throw to remain.
Keep the Host. Any time Deric takes a long rest, he must make a Cha saving throw against Test's Charisma ability score(18).
On a fail, Deric stays as the "host".

Test has a +15.

Deric(as a commoner) has a +1.

Test compleatly overwrites the will of its host. This appears as a normal attunement to all low level divination spells(DM disscretion).

This overwrites all class ablilities and background of the host. It does not overwrite their HP or racial abilities.

Add level 4 Palidin stuff here.
Blah blah stabby valor blah

Movement. One 30ft teleport per day when not bound to a host. Test must be unseen and unheard to use this. When attuned but not "hosted", test can teleport to the their hand if they are unaware.