Wyrmslayer weapons are normally swords of elven design. Elven script flows down the blade, with the crosspiece forged into the likeness of an eagle's beak. As powerful as these blades are in fighting dragons, there is no hiding when a dragon is near. The loud buzzing sound that emanates from the blade itself will wake any nearby sleeping dragon.

You have a +3 bonus to attack and damage rolls made with this magic weapon.

The sword deals double damage to Dragons or Draconians. (+2d6 against dragons)

Thunder Attack: When you hit a true dragon, +10 thunder damage and deafening the dragon like a Blindness/Deafness spell.  

Dragon Enhancement: As a Bonus action, your next attack with this weapon, if made before the end of your next turn against any dragontype, gains a +5 to the attack roll and ignores any resistance the dragon has.

Any character holding Wyrmslayer by the hilt gets a magical protection from dragon breath attacks (+3 to saves vs Dragon Breath). 

Wyrmslayer is immune to the imprisoning effects of dying Baaz Draconians.

Wyrmslayer has the strange tendency to give off a loud buzzing noise when within 30’ of a true dragon (not a draconian). This buzzing always wakes a sleeping dragon.

All dragons of the "old" age category have heard of or seen Wyrmslayer. 

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

Notes: Bonus: Magic, Damage: Slashing, Damage: Thunder, Damage, Combat, Heavy, Two-Handed, Graze