Be careful what you wish for...

[Eönwë]

Originally Posted by Hookbill the Goomba

I wish Dwarves' beards were deadly weapons.

Your wish is granted. The Longbeards then kill all the other clans as soon as they are awakened, so Nogrod is never built and Turin never gets to fight with his Dragon-helm, which means that Glaurung is still alive and eats everyone after Sauron wins without Narsil killing him.
The Longbeards then start stabbing themselves to death and we're already at Dagor Dagorath.

I wish everyone in Middle-Earth only ate fish