Back in the 90's I was a dealer for among other companies, Patu, in fact I still use my Patu DC65, mostly when I'm pruning in my blueberries.
Any way, do you have old dull knives? If yes just sharpen them on a belt grinder. If no knives, then Try J.S. Woodhouse, they were the distributor in the North East US. I think PATU was bought out but knives should still be available.
A Google search will get you to their phone numbers. They only sell thru dealers but they can steer you to a dealer you can get them thru.