Thagomizers are no doubt a cool exotic in both look and function. But it needs a buff.
Thagomizers cater to strikers and we already have enough exotics that do that.
What thagomizers need to do is not just give amplify as a free perk. But give stoke the forge for sunbreakers and unbreakable for defenders. This would make this exotic a strong contender against the armamentarium.