The hilt of this sword bears a carnelian engraved with the blood rune.
You can add your Constitution modifier (minimum of +1) to the damage rolls of attacks made with this weapon.
When you target a creature with an attack using this weapon, you can invoke the sword's rune, causing it to flare with crimson light and infusing your attack with bloodthirsty precision. You then spend and roll one of your unspent Hit Dice and add the number rolled to the attack roll. You can choose to invoke the rune after rolling the d20.
If this attack hits, you can also spend and roll any number of your unspent Hit Dice and add the total rolled to the weapon's damage.
Once the rune has been invoked, it can't be invoked again until the next dawn.
When making an attack with a Finesse weapon, use your choice of your Strength or Dexterity modifier for the attack and damage rolls. You must use the same modifier for both rolls.
When you take the Attack action on your turn and attack with a Light weapon, you can make one extra attack as a Bonus Action later on the same turn. That extra attack must be made with a different Light weapon, and you don't add your ability modifier to the extra attack's damage unless that modifier is negative. For example, you can attack with a Shortsword in one hand and a Dagger in the other using the Attack action and a Bonus Action, but you don't add your Strength or Dexterity modifier to the damage roll of the Bonus Action unless that modifier is negative.
If you hit a creature with this weapon and deal damage to the creature, you have Advantage on your next attack roll against that creature before the end of your next turn.