Yes, this new discovery shows that Egyptians had a much better understanding of weapons manufacturing and iron than we thought. It was once thought that people from that era were unable to heat iron to a high enough temperature in order to shape it. This dagger, and the quality of it, shows how advanced the ancient Egyptians were.
King tut's was a king, if he did make such a thing why am I not surprised. People have to make the highest security things to protect their ruler. Unless the citizens of King Tut's kingdom actually commonly started making it themselves, then no, it may be an important discovery, because it was the only one made.
All other Egyptian weapons would be made out of other materials. King tuts blade was obviously made out of a meteorite because he is a king who, in Egyptians eyes, needs a prestigious blade forged out of the finest resource - a meteorite. It's clear if you think about it. Also considering history is history and there is no changing it based on a meteorological discovery. Unless another blade made out of a meteroite is discovered and it is hundreds of years old, then maybe we could consider meteors being a fraction of historical weapon manufacturing. This is one blade that belonged to a king. It is insignificant.
Science has already shown that one source of gold on our planet comes from meteors and meteorites. Historians have touted the metallurgical expertise of the Egyptians for centuries. They were master goldsmiths. It doesn't take a stretch of the imagination to see that they could have had better weapons manufacturing than we first thought. But change history? No, not change... amend and expand maybe.
While this is an amazing find, I don't believe it is a crucial one. History has many materials that were used for weapon making. While King Tut had a blade made of meteorite, I find it hard to believe that many others did as well. I can not imagine that said material would be an easy find for anyone then, or now.
The discovery that King Tut's dagger blade is made from hammered meteorite will not rewrite the history of weapons manufacturing. Many materials and processes have been used over the years in manufacturing weapons, the fact that King Tut's dagger was made of hammered meteorite will not change that. This discovery may change the future of weapon manufacturing, but history is history and discoveries won't change what has already happened.