Claw of Gel'mar

This greatsword appears to be made of a warped steel, but at a closer look it is bone and platinum fused together.
Dormant: The sword gives the wielder a +1 to attack and damage rolls.
Paralyzing Strike: As a bonus action you can force a creature within 5ft of you to make a Constitution saving throw (DC 13) or become paralyzed for 1 minute. The creature can repeat the saving throw at the end of each of it's turns, ending the effect on a success. You can use this effect once per long rest.
Awakened: The sword gives the wielder a +2 to attack and damage rolls.
Paralyzing Strike: As a bonus action you can force a creature within 10ft of you to make a Constitution saving throw (DC 16) or become paralyzed for 1 minute. The creature can repeat the saving throw at the end of each of it's turns, ending the effect on a success. You can use this effect twice per long rest.
On a successful hit the sword deals an extra 1d6 cold damage.
Exalted: The sword gives the wielder a +3 to attack and damage rolls.
Paralyzing Strike: As a bonus action you can force a creature within 15ft to make a Constitution saving throw (DC 18) or become paralyzed for 1 minute. The creature can repeat the saving throw at the end of each of it's turns, ending the effect on a success. You can use this effect three times per long rest.
On a successful hit the sword deals an extra 2d6 cold damage.
The Call of Black Flame: Critical hits with this weapon are scored at 19-20. Additionally when you hit with a critical hit the target must succeed on a Dexterity saving throw (DC 17) or take 3d12 fire damage-half as much on a success. 

Manufacturing process

Bahamut brought the mass of platinum and bone to his fellow god and friend, Moradin and together the worked the remains into the greatsword. 
Moradin worked the blade for 10 days while Bahamut imbued it with the powers of a Silver Dragon. 
What the two did not foresee were the effects left behind by the Black Flame that had slain Gel’mar. 

History

This greatsword was made from the claw of a silver dragon named Gel'mar who was the first champion of Bahamut. Gel'mar was slain by Drelzad, the champion of Tiamat.
After their battle Bahamut came to retrieve his champion, only to find a mass of platinum and bone melted together by the black flames of Drelzad. With this Bahamut promised to bring an end to Tiamat and her champion. 
It was stolen by agents of Drelzad, the Black Flame Searching for the Chalice of Black Flame over 500 years ago and has since been lost to the ages.

Significance

The sword of the champion of Bahamut.

Item type

Weapon, Melee

Rarity

Legendary

Raw materials & Components

Platinum, Bone from the Claws of Gelmar