Any melee weapon can be a Crystal weapon. These prismatic instruments critically hit on 19-20. When the damage from a critical strike is rolled, you can choose to shatter the weapon, destroying it but dealing double the damage rolled in the process.
Magic Weapon (Special), Legendary (Requires Attunement by a Cleric, Monk, Paladin, or Warlock)
In the ruins of Bellhammer, the once-mighty forge city, lay a broken chapel bell; the material, in the hands of a gifted smith, can be forged into a pair of enchanted caestus. These mighty bronze fists dealt crippling blasts with each strike, the dull tolling of a bell ringing out with every blow.
When equipped as a pair, these gauntlets grant a +2 bonus to attack and damage rolls made with these magic weapons. They are simple melee weapons that deal 2d4 thunder damage on a hit.
Toll. If both gauntlets are equipped, then as an action the gauntlets can be slapped together to create a shattering blast. All creatures, including you, within 10 feet must make a Constitution saving throw with a DC equal to 8 + your Strength modifier + your Proficiency bonus. On a failed save a creature take 2d4 thunder damage and is deafened for 1 minute. The creature may attempt the saving throw again at the end of each of its turns. On a successful save the effect ends.
For Whom the Bell Tolls. Once per day when using Toll, you can channel the Spirit of the Last Vicar into the attack. The range increases to affect every creature except you within a 20 foot radius; the damage increases to 2d6 + 1d6 per player level, and targets who fail their save are stunned. Creatures who save are not stunned or deafened, and take half damage. Stunned creatures can reattempt their save at the end of each of their turns, however once successfully saved the creature remains deafened for an additional minute.
You still have use of your hands while these weapon are equipped, but you cannot effectively wield a another weapon. While equipped you have disadvantage to tool checks, sleight of hand checks, and the use of any other weapon.
Simple Melee Weapon, 2d4 Thunder, Special
Wonderous Item (Gauntlets), Very Rare (Requires Attunement)
These heavy hide gauntlets are edged with feathers and giant teeth. The plates along the top guard are formed of huge carved bone pieces with weathered imagery.
Might. Your Strength score is 19 while you wear these gauntlets. This has no effect on you if your Strength is 19 or higher without them. If your size is large or larger you deal double damage to objects and structures.
Fury. When you are reduced to half health or less you can immediately enter a rage, gaining the following:
You can maintain this rage for a number of rounds equal to your Constitution modifier, after which it ends at the end of your turn. You can extend this rage by spending a hit die for each extra round you maintain it. If you choose to spend hit die in this way you gain 1 level of exhaustion once the rage ends. Once you use this feature you cannot use it again until you complete a short or long rest.
Magic Ring, Rare (Requires Attunement by Jakkin)
This ring grants a +1 bonus to attack and damage rolls with your monk weapon and unarmed attacks. This ring has 1 charge.
This once ordinary ring buzzer has been modified with copper coils that wrap down around the wrist and attach to a expanded power pack on the forearm. The little shock glyph has been replaced with a piece of enchanted topaz that crackles with electrical energy. Esper has lovingly engraved "Abra-ca-fuck-you" in Draconic upon the wrist guard.
When you hit a creature with a melee weapon attack you can spend 1 charge to discharge lightning that chains to nearby foes. The target is struck by lightning; three additional bolts leap from that target to as many as three other targets, each of which must be within 30 feet of the first target. A target can be a creature or an object and can be targeted by only one of the bolts.
A target must make a Dexterity saving throw against your monk save DC. The target takes 2d6 lightning damage on a failed save, or half as much damage on a successful one. This damage increases with your breath weapon attack: 3d6 at 6th level, 4d6 at 11th level, and 5d6 at 16th level.
You can channel your breath weapon into the ring to gain an additional charge. The ring returns to 1 charge after a long rest.
Magic Weapon (Maul), Artifact (Requires Attunement)
This magical weapon appears as a two-handed maul of tarnished bronze, the head of which is shaped like a giant squid grappling a ship.
This weapon gains an enchantment bonus, equal to half your proficiency bonus rounded down, to attack and damage rolls.
Scuttle - 1/day
As an action you cause a wave of thunderous force to sweep out from the hammer. Each creature in a 15-foot cube originating from you must make a Constitution saving throw. On a failed save, a creature takes 2d8 thunder damage and is pushed 10 feet away from you. On a successful save, the creature takes half as much damage and isn’t pushed.
When you use this item, the thunder damage increases by 1d8 for every 2 levels you are above 1st. 3rd level (3d8), 5th level (4d8), 7th level (5d8), 9th level (6d8), 11th level (7d8), 13th level (8d8), 15th level (9d8), 17th level (10d8), and 19th level (11d8)
In addition, unsecured objects that are completely within the area of effect are automatically pushed 10 feet away from you, and unattended non-magical objects in the area take the maximized thunder damage.
Bludgeoning and thunder damage from the hammer is doubled against wooden objects.
If the Krakenhammer is bathed in the fresh blood of a Megladon then the hammer now permanently deals 3d6, and double damage against stone.
Destroying the Hammer
The Krakenhammer must be hung to dry for one month in a smokehouse, alongside dried seaweed harvested from a Kraken's lair. Over this time the Krakenhammer will visibly shrivel, and afterwards it must be kept absolutely dry or the process will need to be started anew. In this state, it can be struck tremendously (DC 20 Strength check) against the top of a mountain, where it will shatter. Once shattered, nothing can repair it.