Short answers, pulled from the story.
The Missouri Supreme Court ruled in 1982 that an ordinary pointed knife with a four- to five-inch blade constitutes a dagger under state criminal code. This legal definition treats the object as a short weapon with a sharp point used for stabbing regardless of whether it has one or two edges.
Copper daggers appeared first in the 3rd millennium BC during the Early Bronze Age. Archaeologists recovered copper daggers of Early Minoan III style between 2400 and 2000 BC at Knossos in Crete.
Researchers confirmed in June 2016 through x-ray fluorescence spectrometry that the iron dagger from Tutankhamun contained similar proportions of metals found in a meteorite discovered nearby. This evidence suggests an ancient meteoritic origin for the blade.
Heavy armor deployment like maille and plate forced a shift toward thrusting attacks since cutting became ineffective against steel defenses. Standard attacks frequently employed the reverse or icepick grip to increase penetrative force against chain mail or plate armor.
British Commando units received the Fairbairn Sykes fighting knife developed by William E. Fairbairn and Eric A. Sykes. Both men gained real-life close-combat experience while serving on the Shanghai Municipal Police Force where Fairbairn engaged in hundreds of street fights over twenty years.