Chaff grenades plus some alternate version of the syringe takes care of the cyborgs. Sam loves his running around the map so claymores take care of him. The syringe, proper timing and a lot of dodging takes care of Armstrong. Plus the nanomachine dolls Screaming Mantis used turns Armstrong into a puppet.
For Mistral, Snake could run around the tower and disable all the Gekkos as an alt strategy.
His eyes are not protected. SAM Dlc also though as that you can injure Armstrong with proper timing.
Proper timing and the HF Murasama.
Unless Snake is given an HFSyringe it's not going to be nearly as simple as Vamp. --- "If someone told me ten years ago that Raiden was going to be cooler than Dante, I would have told you to just shut up and allow me to punch you."