We are not talking about low mass bullets flying at supersonic speed, the soft bullet would be deformed by blasting through the sound barrier and would no longer be small enough to penetrate. We are talking about medium mass object flying at subsonic speeds and constrained enough that it will not easily deform. For example on mythbusters they found no difference in shooting a frozen or thawed chicken through a windshield of an airplane. The damage is done by the impact not a hard object, the blender is not an equal comparison. That is a much lower kinectic energy situation with hardend blades, still the likely result is that the blades get bent from the engine, and dulled from the bones. The aircraft engine uses softer but much stronger blades and the damage is not caused by contact with hard objects but a sudden impact. Yes the motor will nick and cut the blades more than the chicken, but that is minor damage the engine will run through. It is total breakage and missing blades that will do the jet engine in, not cuts and nicks.