Language. Deric can speak, read, and write common.
Arcane Blindsight(15ft). You can't discern color or invisible things. Additionally, test can use the senses of Deric.
Steel Soul. Test's creature type is construct. Healing potions and spells don't work on Test, 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. If Test Critically Fails, Deric takes 1d4 slashing damage.

Keep the Host. Any time Deric takes a long rest, he must make a Cha saving throw against Test's KH(24). On a fail, Deric stays as the "host" and Test completely overwrites his free will.
Test's KH(keep host) is 10+cha and each time the host fails the save, test gains a +1 to its KH up to a maximum of +10. Test looses its KH bonus if the host is lost. Creatures immune to charm are immune to this.

Test overwrites all Class Features and Feats of the host but not their HP, AC, or Racial Abilities. All INT, WIS, and CHA ability checks(with the exception of Keep the Host) are to be made using Test's Ability scores.
Add level 4 Paladin stuff here.
"Blah blah stabby valor. I'm not making an entire paladin for this." - Deem Leem

Basic Magic Weapon Stuff

Weapon Description: A basic longsword whoose blade is engraved with a paladins oath. Properties: Versatile (1d10)
Deric has a +1 bonus to attack and damage rolls made with this magic weapon.
Versatile (1d10) Can be 2-handed to increase damage to 1d10.