Many of us have those little utility knives with multiple snap off blade pieces, so we can break them when the blade gets dull. The problem is trying to snap a bit of blade with pliers, tapping with a hammer, using a rag or other protective material.
If you look close, a
good number of those products have a removable tip at the other
end that is to be used to snap off the blade. Pop off the tip,
insert the blade into it and snap. Wow, easy.