Blood Of The Fiend

As a bonus action, you can coat your weapon in your blood (whether from an open wound or from cutting yourself).

1d4 damage if cutting self

You can use the poison to coat one weapon or up to three pieces of ammunition.

A creature hit by the poisoned weapon or ammunition must succeed on CON saving throw equal or greater than your spell save DC, or take 1d4 additional poison damage and gains the poisoned condition for one round (A poisoned creature has disadvantage on attack rolls and ability checks.)

Once applied, the poison retains potency for 1 minute before drying.

You are immune to the poison condition and resistant to poison damage with this feat