Antimagic Immunity. Although magical in origin the Triple bladed greataxe, morningstar, jackhammer, spikey lance, rapier, scimitar, shortsword, javelin, hammer, trident, warpick, sword is immune to the dispel magic feature. Meaning that it maintains all its functions even if the spell is successfully cast on it. A wish spell however can rid the Construct of its sentience for 1 minute. When in this state the Construct is considered paralysed. 

Bad False Appearance. While the sword remains motionless and isn't flying, it is indistinguishable from a Weapon. However it looks nothing like a normal weapon so who in their right mind is not going to inspect it.

Screams of Infinite Pain. All creatures within 100ft of Aaron's Sentient Triple bladed greataxe, morningstar, jackhammer, spikey lance, rapier, scimitar, shortsword, javelin, hammer, trident, warpick, sword, when in combat must make a DC 15 Constitution saving throw. On Success they become immune to this feature for 1 hour, but on failure they become defend till a short or long rest.

True Form of Pain. When Aaron's Sentient Triple bladed greataxe, morningstar, jackhammer, spikey lance, rapier, scimitar, shortsword, javelin, hammer, trident, warpick, sword, reaches 0hp It becomes The Triple bladed, Spined Demon of a thousand Weapons. See stat block for details. The DM can decide whether or not the weapon transforms In Front of the party, or if its new form appears in the Demonic plane.

MultiAttack. Aaron's Sentient Triple bladed greataxe, morningstar, jackhammer, spikey lance, rapier, scimitar, shortsword, javelin, hammer, trident, warpick, sword makes four attacks. 2 Spins of Slashing, and 2 Devastating Smashes.

Spin of Slashing. Melee Weapon Attack: +8 to hit, reach 10 ft., one target. Hit: 34 (6d10 + 4) slashing damage.

Devastating Smash. Melee Weapon Attack: +8 to hit, reach 10 ft., one target. Hit: 28 (4d12 + 4) Bludgeoning damage.

Thrust of Piercing. Melee Weapon Attack: +8 to hit, reach 10 ft., one target. Hit: 28 (8d8 + 4) Piercing damage.

Aaron's Sentient Triple bladed greataxe, morningstar, jackhammer, spikey lance, rapier, scimitar, shortsword, javelin, hammer, trident, warpick, sword has four legendary actions, it chooses from below. Only one Legendary action option can be used per turn. The construct regains all spent Legendary actions at the start of its next turn.

Thrust of death (Cost 2 Actions).  Aaron's Sentient Triple bladed greataxe, morningstar, jackhammer, spikey lance, rapier, scimitar, shortsword, javelin, hammer, trident, warpick, sword, moves up to its movement then makes a Thrust of Piercing attack. When it moves in this way opportunity attacks can't be made against it.

Gargantuan Smash (Cost 4 Actions). Aaron's Sentient Triple bladed greataxe, morningstar, jackhammer, spikey lance, rapier, scimitar, shortsword, javelin, hammer, trident, warpick, sword, slams itself down onto the ground releasing a small tremor. All creatures within 20ft of it must make a DC 18 Dec Saving throw. On a fail they take 4D12 Force damage, taking half as much on success.