Flamethrower Chainsaw Guitar!

melee weapon (martial, glaive)/adventuring gear (instrument) Item Rarity: Legendary (requires attunement) Damage Type: Slashing Properties: Special, Heavy, Reach, Two-Handed Weight: 8 pounds This item functions as either a musical instrument, a +2 to hit and damage glaive, or be used as a spellcasting focus for any spells its wielder casts, adding +1 to the attack rolls and DC of the spell when used as the focus.
You have advantage on Performance checks you make while playing this instrument, and can always treat a score of 7 or lower as an 8.
When making a melee attack with this weapon, you can activate the saw blade as a bonus action, dealing an additional 2d4 slashing damage on the next hit attack with this weapon this turn. If you score a critical hit while attacking in this way, the target gains one point of exhaustion. You have advantage on any Intimidation checks you make while revving up this weapon.
As an action, you can cause the flamethrower at the head of the guitar to project fire in a 10-foot cone. Each creature in that area must make a DC 17 Dexterity saving throw, taking 2d8 fire damage on a failed save, or half as much damage on a successful one. Alternatively, you can activate the flamethrower in a spinning motion, exhaling fire in a 5-foot-radius sphere centered on you instead. Once you’ve used either of these properties 5 times combined, you can’t do so again until you finish a long rest.
Lastly, you may add your Charisma modifier to the damage of any attack roll spells cast through this item, as long as the spell doesn't have a range of touch. This damage may not apply more than once per spell, such that for, for example, you do not add your Charisma modifier to each damage instance of Scorching Ray, only the first of them.

(Suggested Price, 40,000 GP.)