Appearing as the rustiest and possibly dullest blade anyone could thing of, Zälterling is surprisingly as sharp as any common dagger.

It's magic prevents any damage to it, and resist any foreign attempt to change it's form, but doesn't (yet) allow bypassing magical resistances. 

Casting Identify on the rusty dagger reveals only it's name and it's apparent indestructibility.

Blade of blades: Zälterling grows stronger by absorbing magic from other blades. By lying this blade over any other magical blade for 8 hours allows Zälterling to absorb the other blade's magic, both beneficial and curses.

Zälterling needs to absorb

• a +1 blade to advance to become Dormant
• a +2 blade and at least two uncommon blades to become Awakened
• a +3 blade and at least three rare blades to become Exalted

The ritual must be finished without interruption or it fails. If successful, it renders the other blade completely non-magical. It can only absorb the same enchantment once.

It will not absorb power from any sentient weapon, because it consideres them it's kin.

Sentience: Zälterling is a sentient neutral good weapon with an Intelligence of 18, a Wisdom of 15, and a Charisma of 19. It has hearing and darkvision out to a range of 120 feet.

The weapon communicates telepathically with its wielder and can speak, read, and understand Celestial, Elvish, and Sylvan.

Personality: A spriritual ancestor of all living blades lives within Zälterling. The weapon values valour, achieving greatness and gaining strength. It compliments its wielder whenever they achieve victory and takes pleasure in helping others. It is at odds with evil sentient blades, and wants to stop them and their wielders. 

Dormant

The blade grants the following benefits in its dormant state:

• You can speak, read, and write Sylvan
• You gain a +1 bonus to attack and damage rolls made with this magic weapon. 
• While holding this weapon, you can as a free action change it's form between a dagger and a shortsword. The blade uses normal statistics of either chosen form. This can only be done once per turn.
• While attuned, you can pick any absorbed uncommon blade and use it's magical properties as if they were on this blade. This can be changed after a long rest.

Awakened

When the Blade reaches an awakened state, it gains the following properties:

• The weapon’s bonus to attack and damage rolls increases to +2.
• While holding this weapon, you can as a free action change it's form between a dagge, a shortsword, and a longsword.The blade uses normal statistics of either chosen form. This can only be done once per turn.
• While attuned to the Blade, you can pick any one uncommon and one rare magic weapon the Blade has absorbed and use their magical properties as if they were on this blade. This can be changed after a long rest.

Exalted

When the Blade reaches an exalted state, it gains the following properties:

• The weapon’s bonus to attack and damage rolls increases to +3.
• While holding this weapon, you can as a free action change it's form between a dagger, a shortsword, a longsword or a greatsword. The blade uses normal statistics of either chosen form. This can only be done once per turn.
• While attuned to the Blade, you can pick and combine one uncommon, one rare and one very rare weapon and use their magical properties as if they were on this blade. This can be changed after a long rest.

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

Notes: Language: Sylvan, hero with a great destiny., Finesse, Light, Thrown, Nick