Breath of the Sea

This double-bladed scimitar deals 2d4 slashing and an additional 1d6 fire and 1d6 cold damage for each hit. 

You can use your action with this weapon to cast cone of fire and ice. A blast of cold and hot air erupts from the blades. Each creature in a 60-foot cone must make a Constitution saving throw for DC 15. A creature takes 3d8 cold and 3d8 fire damage on a failed save, or half as much damage on a successful one. This feature recharges after a long rest and is only usable when you have the single blade, 'Breath of the sea'.

You can use a bonus action to split this weapon into two single blades. The 'Breath of the North' and the 'Breath of the South'. It takes another bonus action to put the blade back together. 

Each of these scimitars deals 1d6 slashing damage and an additional 1d8 cold for 'Breath of the North' or 1d8 fire damage for 'Breath of the South'. When you choose the attack action you can use these blades to shoot a bolt made ouf of fire or ice with a range of 60 ft. that either deals 1d10 cold or 1d10 fire damage, depending on wich of the blades is being used.You have a +3 bonus to attack and damage rolls made with this magic weapon.

The double-bladed scimitar is the signature weapon of Valenar elves. A haft of fine wood supports a long, curving blade on either end. Forged with techniques honed over centuries, these blades are strong, sharp, and remarkably light. Each scimitar is a masterpiece, and as a result the double-bladed scimitar is an expensive weapon (100 gp) — few though ever have the opportunity to purchase one. A Valenar blade in the hands of a non-elf is generally assumed to have been stolen or looted from a fallen foe, and a Valenar elf might feel entitled to demand its return or challenge the bearer to prove they’re worthy to wield it.

Special. If you attack with a double-bladed scimitar as part of the Attack action on your turn, you can use a bonus action immediately after to make a melee attack with it. This attack deals 1d4 slashing damage on a hit, instead of 2d4.

Notes: Bonus: Magic, Damage: Cold, Damage: Fire, Damage, Combat, enchantment, Special, Two-Handed