New magic item (unsure if this is the right place)

[Diomitus]

I'm not sure if this is the right place to post this but I thought I'd try.

Artifact: granted at level 1 (please read all before you judge haha)
Sentient Greatsword

Alignment: Lawful Good

Requires attunement by creature of lawful good alignment who is proficient in all martial weapons and armor.

If creature who is not LG/LN picks up the weapon, it must make a Str/Dex save each turn it holds the sword.

NG: DC 5 or 4 points of slashing damage
CG: DC 10 or 4 points of slashing damage
N: DC 10 or 8 points of slashing damage
CN: DC 15 or 12 points of slashing damage
LE: DC 15 or or 18 points of slashing damage
NE: DC 20 or 20 points of slashing damage
CE: DC 25 or 24 points of slashing damage

If the creature takes damage it drops the sword.

A large or smaller creature of evil alignment rolls a 1, roll a d6. On a 1, the limb they use to pick the sword up is severed from their body.

The sword is linked to the mind of its wielder.* It communicates telepathically/emotionally to wielder who is attuned to the sword.

The sword has hearing and normal vision to 60 feet and darkvision out to 30 feet.

The sword seeks to protect its wielder and destroy all evil creatures.

The sword functions similarly to a moonblade.
There are 5 runes on the blade.

1st: +1 to attack and damage
2nd: +2
3rd: +3 and sentience awakens
4th: extra 1d6 fire dmg & bypasses fire resist
5th: Gains properties of a Vorpal Sword

If the creature attuned to the weapon must prove themselves wanting to become the next wielder of the weapon. The DM must ensure that the wielder has been following lawful good behavior. If they have, the runes activate and glow in radiant light.* The runes activate one at a time at level 4, 8, 12, 16, and 20. If they act contrary to the swords alignment, the* runes burn out until the creature proves itself worthy again. Until they do, they are unable to wield the sword as seen above in the alignment/damage chart.

Sword also has a split property.
Using a bonus action, the wielder can split the greatsword into 2 shortswords allowing 2 weapon fighting, dual wielder, and defensive duelist feats.
The wielder must use an action to reunite the 2 swords into the greatsword.

edit My question is what you fine people think of this?
Is it balanced, over powered, acceptable scaling, etc

[Zacchaeus]

What's the question?

[Diomitus]

Guess that would help too!
I'm just curious of what people think of this.
Balanced, effective, etc

[Zacchaeus]

I like the idea that a weapon grows with the player; what you have is balanced as far as I can see depending on the levels that new attributes unlock. You could also use it to foreshadow upcoming adventures in your campaign (sword nudges the character to a particular location/slaughter a particular bad guy, rescue a princess in a tower - wait; no on that last one )

[Bidmaron]

Zacchaeus, what do you have against princesses? Or is it towers?

[Zacchaeus]

Yep, it's towers

I've had bad experiences with towers

[Diomitus]

It's not the towers so much.
It's all those stairs!