Quoted from Arcade:When I say blade fuse, I am not talking about the little plastic U shaped push in fuses for cars.
However the metal end of one of those fuses is a great example of what is inside the NB fuses that Williams used.
It is a normal looking glass fuse but it has a "metal blade" inside it, not a wire like regular fuses have.
Actually I believe what you are seeing that you call bladed is just the higher am fuses. Some manufacturer use 'flat' filaments instead of 'round' drawn out wire. And on the flat ones they tend to change the width of the 'waist' to change to rating.