Attacks you make using this magical weapon deal an additional 1d4 cold damage with each hit. You have a +1 bonus to attack and damage rolls made with this weapon.
This icy whip has 3 charges that are replenished each dawn. When you hit a creature that is not immune to cold damage with this weapon, you can expend a charge to inflict a biting chill, causing the creature to make a DC16 Constitution saving throw. On a failure, its speed becomes 0 until the start of your next turn. On a success, its speed is halved instead.
Once you attune to this weapon, its once frigid handle feels warm and welcoming to your touch.
Proficiency with a Whip allows you to add your proficiency bonus to the attack roll for any attack you make with it.
This weapon has the following mastery property. To use this property, you must have a feature that lets you use it.
Slow. If you hit a creature with this weapon and deal damage to it, you can reduce its Speed by 10 feet until the start of your next turn. If the creature is hit more than once by weapons that have this property, the Speed reduction doesn’t exceed 10 feet.
Notes: Damage, Control, Movement, Combat, Finesse, Reach, Slow
Perhaps creatures with resistance to cold damage could have advantage on the saving throw to resist the whip's effect?
Love the flavour of this. Would it be ok to add the base damage to it for clarity? I also agree that those resistant to cold should have advantage on the save.