I hadn't seen this question asked before but it's entirely possible I missed it. To clarify, I mean giving one's personal weapon a name, rather than a class of weapons.
What are the oldest weapons we know the names of? Do we still have any historical weapons we know the names of? Were there certain cultures in which naming weapons was a more common practice than others? Are there any records of non-standard (e.g. not a sword or, more recently, firearm) weapons that had names?
The oldest instance of a named weapon that I know of comes in the account of the taking of Joppa from the New Kingdom period of Egypt: http://www.reshafim.org.il/ad/egypt/texts/the_taking_of_joppa.htm
So they came, and hobbled their horses, and gave them provender, and one found the great cane of Men-kheper-Re and came to tell of it to Djehuti. And thereupon the Foe in Joppa said to Djehuti: " My heart is set on examining the great cane of Men-kheper-Re, which is named ......tautnefer. By the ka of the King Men-kheper-Re it will be in thy hands to-day ; now do thou well and bring thou it to me."
Sadly, the text is damaged, so we don't know the full name of the staff or whatever supposed magical powers it may have had.
There are LOTS of historical named weapons we still have. The Seven Branched Sword of Japan is one: http://en.wikipedia.org/wiki/Seven-Branched_Sword
There's a fairly large number of preserved Japanese swords from various periods, both named and unnamed. Kusanagi, part of the Imperial regalia, may or may not still exist. Some historians think it was lost during the battle of Dan no Ura (or even before,) when the child-emperor of Japan was drowned at sea. The Japanese claim that they still have the sword, but nobody except the emperor and the attendants of the Atsusa shrine are allowed to see it.
hi! a few more examples can be found in these threads
Are there any examples of named swords in history?
Could the legend of Excalibur have come from an Ulfbert sword from the viking era?
Why would some knights during the Middle Ages name their weapons?