Avengers: Earth's Mightiest Heroes was the debut of the Vibranium daggers.
Priest is also responsible for the Energy Daggers and they have appeared multiple times in the comics before the Earth's Mightiest Heroes cartoon and afterwards.
Yes, I am double dipping with this poorly made article.
The Energy Daggers were introduced by Mr. Priest 14 years before Avengers Earth's Mightiest Heroes...
|Black Panther, vol 3, #1|
Hudlin used them four years before Earth's Mightiest Heroes...
|Black Panther, vol 4, #34|
Hell, T'challa even used energy daggers in Ulton Unlimited, one of the most popular Avenger's arcs of all time, 13 years before Earth's Mightiest Heroes...
|Avengers: Ultron Unlimited|
I love EMH, and it features one of my favorite Black Panther characterizations ever, and actually got me into the character, but... it did not debut or popularize the energy daggers. At all.