I have shipped multiple Japanese saws which are delicate of course (when run over by a forklift, for example).
Agree with everything David said. Couple of minor additions:
1. If the styrofoam between blades leaves the handles in mid-air, support them with something, so they have no degrees of freedom to move.
2. (optional). Consider a package stiffener, so that the saws aren’t taking the bending load when the package gets thrown around at the airport.