American cable housings (3/16ths nylon tubing), I slice with a single edge razor. The foreign (bicycle cables) I cut with an extremely good pair of side cutters (Channel brand) which cut cleanly and I then force a pointed scribe into the end, so there is no binding.
The inner cable gets cut with the side cutter and the end gets soldered about 3/8ths inch before it frays. Solder then cut might work better.
Fill the tubing with TriFlow (Teflon lube) before inserting the inner cable.