meuharris wrote:

I got a garden knife some years (10?) ago and it was the sharpest I
had ever used -like cut glass. .
It was serrated and it would cut through small branches like butter
(we used them for pruning young trees)
The downside was it was really brittle and if you were tempted to
push it instead of drawing it towards you it would snap.
Would that have been a carbon steel blade?
Where could I order them from (I don't seem to have much joy in
googling *carbon steel blade* so maybe it is some other manufacturing
method.....

Are you sure this was a knife and not a pruning saw?

For knives, I would be surprised if you couldn't find a particular style
of knife he

http://www.worldknives.com/catalog.php

But I have the suspicion that what you actually had was something like
this:

http://tinyurl.com/6smpxf

http://tinyurl.com/94rtqy

These look like folding knives but they are saws that cut on the pull
stroke. The design of the teeth gives a smooth cut and it takes very
little effort to cut through even thick branches. As you say, the blades
are usually high carbon steel and they are brittle and can be easily
broken.

I prune several hundred trees a year and use a combination of a chainsaw
and one of the Felco folding pruning saws. Felco tools are fairly
standard for professional use, since they offer a good price/performance
balance.