Aeglos

Aeglos is a glaive with a silver shaft, a white head (blade), and golden highlights. The head has the following inscription written in celestial on one side and elvish on the other: "When the point of my blade reaches my foes, they shall know my name, Aeglos." You have a +3 to hit with Aeglos. Aeglos does an extra 2d8 cold damage. When you hit a target, that target must make a DC Constitution saving throw equal to or greater than your attack roll for that attack. If the target fails, then it takes another 3d8 cold damage. If the target fails by 10 or more, then it becomes frozen (the target's movement speed is reduced to 0 for 3 turns, or until it takes fire damage, or if it is warmed by fire for 1 hour). If target succeeds, then it does not take extra damage or become frozen. When you hit a target that is frozen or deep frozen, and they fail the saving throw, then that target takes 5d8 damage instead of 3d8 damage. If the frozen target fails the saving throw by 5 or more, then it becomes deep frozen (target's movement speed is reduced to 0 and becomes vulnerable to cold damage for 3 turns, or until it takes 35 fire damage, or if it is warmed by fire for 35 hours). If you rolled a natural 20 on the attack roll, then the target automatically fails the saving throw and is subjected to the effects of failing the saving throw by 10. You cannot inflict the frozen or deep frozen effect on a target that you applied either condition to during your current turn. 

Proficiency with a Glaive allows you to add your proficiency bonus to the attack roll for any attack you make with it.

Notes: Damage: Cold, Bonus: Melee Attacks, Damage: Cold, Damage: Cold, player, Damage, Combat, Heavy, Reach, Two-Handed, Graze