Anaklusmos, The Kraken's Key

Anaklusmos, the Kraken's Key, attunes to you. It can only attune one wielder at a time.

Spirit of Water. You have a +3 bonus to attack and damage rolls made with this magic weapon. This blade has the finesse property. You gain an innate swimming speed of 30 feet. You can breathe underwater. As an Action, you can give yourself the effect of the water walk spell at will. You may gain the effects of the spider climb spell on yourself at will.

The Tide Holds. Allies of your choice within 30 feet of you treat any d20 roll of 9 or lower as a 10 on saving throws.

The Water Interposes. Once per round, when a creature you can see within 30 feet takes damage, you may interpose the tide: the damage is halved. This requires no reaction. If the damage would still reduce an ally to 0 hit points, you may instead take the remainder yourself.

The Current Carries. As a bonus action, choose one willing ally within 30 feet: their speed is doubled until the end of their next turn, their movement does not provoke opportunity attacks, and they may immediately move up to their normal speed.

The Tide Turns. As a bonus action, command an ally who can see or hear you; they may use their reaction to make one weapon attack. You may use this feature a number of times per day equal to your proficiency bonus.

The Blade Invests in its Wielder. When you attune to this blade, you may immediately gain four feats. Each time you level up, you also gain an Ability Score Improvement or a Feat in addition to your standard class features. You may spend a minute examining a weapon, armor set, set of tools, or magical item; if you could reasonably utilize the item in question, you gain proficiency with it. You may ignore all class, race, and level requirements on the use of magic items.

The Blade Sustains its Wielder. You are immune to poison damage and the poisoned condition. You are immune to all diseases. You age at a much slower rate. When resting, you may remove all levels of exhaustion after a single long rest. Exhaustion gained from the Avatar of Madness explicitly cannot be removed by this feature.

The Depths Conceal. Scrying spells targeting the holder of this blade automatically fail, and their location cannot be ascertained by any form of magic. Divination magic of any kind cannot perceive the Serpent of Madness within the wielder.

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

Notes: Damage, Combat, Warding, Finesse, Light, Vex