In reply to Dell:
According to the Royal Mail website
Sharp objects (including scissors and kitchen knives or utensils and gardening tools)
Are allowed in the mail both for International & UK destinations
With restrictions and packaging guidelines below:
Wrap heavy cardboard around sharp edges and points, strong enough to ensure that the contents do not pierce the outer packaging.
Wrap each item with cushioning material.
Place in a suitable outer container such as a padded envelope.
The sender's name and return address must be clearly visible on the outer packaging.
I have recieved and shipped a number of Ice Axes over the last two years with no issue
My advice would be to go to another postoffice or use AN Other courier