Wow. Seems that Fiskars only has one blade size/type available.
Clauss has a replaceable blade model, but Northern Tool says the blades are no longer available.
It appears that "Consumer products" are designed to be
consumed.
Corona Tools offers several models with replaceable blades (and even sells replacement blades, unlike other manufacturers).
Corona Tools - replacement parts
It appears that the replacement blades are almost as expensive as the tools themselves.
What I would suggest, is to go to your favorite store, and tell them that you want to buy a new set of pruners
and a replacement blade. The sale is dependent on you walking out of the store with
both. If I couldn't get
both, I would walk out empty handed.