I can easliy understand why manufacturers wouldn’t want to give out 3D drawings of their knives or even their blades. 3D drawings can be directly loaded into manufacturing software for duplication on NC equipment.
However, they should be able and willing to give you simple 2D drawing exchange files with a profile of the edge. With that and the depth at the heel, you ought to have what you need.
Try asking for a 2D drawing of the blade alone.