I want feedback on a weapon.

Destreza Dagger

Weapon (dagger), rare (requires attunement by a creature with Martial Weapon proficiency)

A finely crafted enchanted dagger designed for skilled duelists. Rather than relying on brute strength, the weapon enhances its wielder's precision, reflexes, and ability to deflect incoming blows.

Weapon Properties: Finesse, Light, Nick (Mastery)

Enchanted Weapon

You gain a +1 bonus to attack and damage rolls made with this magic dagger.

Destreza Parry

When you are hit by a melee attack while wielding this dagger, you can use your reaction to roll 3d6.

Against a Normal Hit:

- At least one 6: The triggering attack misses instead, dealing no damage and negating any effects that require the attack to hit.

- At least one 4 or 5, but no 6: The damage from the triggering attack is halved.

- All dice show 1, 2, or 3: The attack deals its normal damage.

Against a Critical Hit:

- At least one die shows 4, 5, or 6: The damage from the critical hit is halved.

- All dice show 1, 2, or 3: The critical hit deals its full damage.

A critical hit cannot be turned into a miss through this property.

Limited Uses

You can use Destreza Parry a number of times equal to your Dexterity modifier (minimum of once).

You regain all expended uses when you finish a Long Rest.

A use is expended regardless of the result of the dice.

I also have proposed very rare and legendary versions if you guys would like a better idea of where this is going. 

This is pretty good, but there are a few errors and things that I think could be improved.

First, a Dagger is a Dagger. You don't need to remind everyone what its properties are from being a Dagger, especially if you aren't going to include its damage die.

Second, rolling 3d6 and looking at all of the dice to see what particular outcome you got seems like kind of a lot to do as a reaction. One die can get similar numbers and be way easier to handle.

Third, uses and recharging for magic items are ALWAYS based on events and numbers outside of the character.

Here's what I personally think it should look like:

Destreza Dagger

Weapon (Dagger), Rare (requires Attunement by a creature that is proficient with Martial weapons)

You gain a +1 bonus to attack and damage rolls made using this weapon. Additionally, it has 3 charges and regains all expended charges daily at dawn. When a creature you can see hits you with a melee attack while you are holding the dagger, you can expend one charge as a Reaction to roll 1d8. If you roll a 1, you suffer the normal effects of the attack. If you roll a 2-5, you halve the damage you take from the attack. If you roll a 6-8, the attack misses. If the attack was a Critical Hit, a roll of 6-8 has the same effect as rolling a 2-5.

Notes: All dice rolling 3 or less has a 12.5% chance of happening, same as rolling a 1 on a d8. Rolling a 4 or 5, 45.37%. 2-5 on a d8 is a 50% chance. Rolling a 6, 42.13%. 6-8 on a d8 has a 37.5 % chance.