There has been a strong association with tools and weaponry throughout the years. Change of use inspired development, and axes become battle axes, Hammers become War Hammers, rice flail become Nunchaku, Kama (japanese sickle) became kusarigama and there are many more examples of this are out there.
Objects become weapons when they are used as such, otherwise they are inanimate objects, they have no will of their own or ability to move without outside intervention.
What I find annoying is that for an axe in my possession to be classed as an offensive weapon someone has to believe that I have intent to use it as such, either that or they don't understand the nature of the object.
Swords, bows and firearms have a place within the sporting society, axes and knives have a place as tools, explosives have a place within industry and entertainment (fireworks), the nature of the object only changes to being a weapon when the person using it has intent to use it as such.
Obviously the transportation of some objects (chemicals and the like) can be dangerous / hazardous and as such they should be listed as items that require specialist carriage, but properly packaged cutting tools shouldn't be on the list.
With the list that a lot of the carriers are using (it's not just Royal Mail) technically you'd have to remove all of the knives from a canteen of cutlery, chefs knives would be a prohibited item and there would be a host of other items that are everyday things that couldn't be shipped including batteries, which in today's society would spell disaster for anyone sending for a new phone, tablet or laptop.
Common sense appears to have been binned.