Stalagmight

Weapon (lance, spear, or pike), rare (optional attunement)   Legends say that the shaft of paladin’s holy spear lies at the centre of this jagged length of calcium carbonate. Twisted by aeons on the plane of earth, the restorative magic is said to have been corrupted, leaving a horrifying weapon with the ability to turn flesh to stone.   Stonestrike. When you hit a creature with this weapon, its speed is reduced by 10 feet until the end of its next turn as its skin and joints become stiff and unmoving. A creature whose speed is reduced to 0 feet in this way is restrained until the end of its next turn.   Optional Attunement. If you choose to attune to this weapon, it gains the Greyscale property while you remain attuned to it.   OA: Greyscale. When you hit a creature with this weapon, you can use a bonus action to cause the target to make a DC 15 Constitution saving throw as you unleash the full petrifying potential of the magic within. A creature that fails the save begins to turn to stone and is restrained. The restrained creature must repeat the saving throw at the end of its next turn, becoming petrified on a failure or ending the effect on a success. If the creature is physically broken while petrified, it suffers from similar deformities if it reverts to its original state.   The petrification lasts until the creature is freed by the greater restoration spell or other magic, or you petrify another creature using this weapon. Once you activate this property, you can’t do so again until the following dawn. Very rare variant: You have a +1 bonus to attack and damage rolls you make with this weapon (unattuned). Increase the DC of Greyscale to 16. You can activate the Greyscale feature twice per day.   Legendary variant: You have a + 2 bonus to attack and damage rolls you make with this weapon (unattuned). Increase the DC of Greyscale to 17. You can activate the Greyscale feature thrice per day.