Armament of the Demigod (Right arm)

This replacement arm was made using the magical energy lying within a dead creature that took the arm in the first place. The magic within the arm tether and mesh with the wearer, effectively meshing the material of the arm with the wearer's flesh. The rarity of this item is determined by the size and CR of the creature used to make it. Sizes provide a number, as shown in the following table. In the second table, CR intervals determine more numbers. The total number is what is used to calculate the rarity. 

Small or lower: 1

Medium: 2

Large: 3

Huge: 4

Gargantuan: 5

CR 5 or less: 5

CR 6-10: 10

CR 11 - 15: 15

CR 16-20: 20

CR 21 or higher: 25

Rarity Chart

Common: 6

Uncommon: 7-12

Rare: 13 - 18

Very Rare: 19 - 24

Legendary: 25 - 30

The Rarity of this item determines the benefits it bestows, besides just the replacement arm.

Common: +1 to AC.

Uncommon: +1 to AC, Can store one 1st level spell from any spell list.

Rare: +1 to AC, Can store one 5th level spell (or upcasted to 5th) from any spell list (the dawn after casting it, a new spell can be stored, but it must be a different spell)., Melee weapon attacks made with this arm have +3 to hit and damage.

Very Rare: +1 to AC, Can store one 5th level spell (or upcasted to 5th) from any spell list, Melee weapon attacks made with this arm have +3 to hit and damage, you gain advantage on Strength saves and athletics checks made to grip, squeeze, or hold things, as well as rolls for throwing non-weapon objects (+2 to the result, as well).

Legendary: +1 to AC, Can store one 5th level spell (or upcasted to 5th) from any spell list, weapon attacks of any kind made with this arm have +3 to hit and damage, you gain advantage on Strength saves and athletics checks made to grip, squeeze, or hold things, as well as rolls for throwing non-weapon objects (+2 to the result, as well), and you can use this hand as an arcane focus for spells that deal specific types of damage, or have specific ranges (you roll the damage/type when you attune to this item; the dice is a d6: 1: Lightning, 2: Fire, 3: Cold, 4: Water-based spells [Tidal Wave, Watery sphere, etc.], 5: Earthen spells, 6: Touch spells) When you cast spells this way, they behave as the Twinned Spell metamagic (touch spells simply chain to the next closest creature) if it is a ranged spell attack, and is a Heightened Spell metamagic if it forces a saving throw. Additionally, if the lost arm was the dominant arm of the one attuned to this item, all spells cast with this hand will use the Subtle Spell metamagic, casting without somatic nor verbal components.

Notes: someone who possesses divine blood.