Switch Axe

Weapon +1 Magical Greatsword/Greataxe (+4 when under benefits of the Greataxe) Varies (this item requires attunement) [6 Hours of free time to learn how to use the weapon]

A large mechanical great sword (+1) that can switch to a great axe through mechanical means. Every 2 successful hits with the great sword in an encounter, you can use a bonus action to switch this weapon into a great axe through non-magical means. The first 2 successful hits in great axe configuration deal an extra 1d8 fire damage, and has a +4 to hit. After 2 successful hits, the great axe no longer deals extra damage, and only has a +1 to hit. This can be repeated in the same encounter to receive the same benefits, though 2 hits in great sword mode must be made again to receive said benefits.