Weapon’s Woe

You imbue a weapon that you can see within range with the sorrow of the souls of the enemies that it has killed.

For the duration of the spell damage dealt by the weapon deals an extra 1d6 necrotic damage.
if an enemy was slain by the weapon within the last minute or in the duration of this spell add an extra 1d4 necrotic damage

At higher level

• choose an extra weapon for each spell slot above 1st level used to cast this spell 
• at a slot of 5th level and above it deals 2d6 and 2d4 necrotic damage 

Specifications 

• Activates only once per turn 
• can activate on reactions 
• Doubles on crits
• can be casted onto unarmed attacks as well ( would have to specifically choose unarmed attack instead of a weapon) 
• For Dual wielders each both weapons count as separate 
• the weapon must’ve been used to kill at least one enemy above CR0 
• A bow/crossbow counts as the weapon not an arrow , for thrown weapons each munition counts as a separate weapon 

(This is my first time creating home brew anything so please feel free to share feedback on what I can balence/ improve)