Source: Arcana Unleashed
Weapon (Dagger), Rarity Varies (Requires Attunement)
The hilt of this magic weapon is adorned with ornate, decorative keyholes outlined in golden filigree.
Three (Uncommon). Three ornamental keyholes adorn the weapon’s hilt.
You have a +1 bonus to attack rolls and damage rolls made with this magic weapon. When you take the Attack action, you can transform this weapon into a Handaxe or Mace. It remains transformed in this way until the start of your next turn, at which point it reverts back to its Dagger form. Regardless of the weapon’s form, you can use your choice of your Strength or Dexterity modifier for the attack and damage rolls; you must use the same modifier for both rolls.
Ten (Rare). Ten ornamental keyholes adorn the weapon’s hilt. Your bonus to attack rolls and damage rolls made with this magic weapon increases to +2. Additionally, when you transform the weapon, you can now transform it into any Simple Melee weapon.
Many (Very Rare). Overlapping ornamental keyholes adorn the weapon’s hilt in a dizzying pattern. Your bonus to attack rolls and damage rolls made with this magic weapon increases to +3. When you transform the weapon, you can now also transform it into a Battleaxe, Longsword, Rapier, Scimitar, or Warhammer.
Additionally, when you miss with an attack roll using this weapon, you can reroll the attack, potentially turning the miss into a hit. You must use the second roll. Once used, this property can’t be used again until the next dawn.