I know you asked about "knives", but your focus on functionality seems to be "rope/line cutting ability, be able to slice through clothing, resist rusting", and emergency response/rescue.
Consider this Benchmade 7hook as an alternative or supplement to a knife:
Benchmade 7 Rescue Hook Strap Cutter X15-TN Steel 4.3" Overall, Black Sheath, Orange Handle Model 7H20W - Knifecenter.com
This particular model is made of a corrosion-resistant alloy, and that seller has about the best price I've seen. I was pointed to them by someone else here on SB.
Comes with a pretty secure sheath system. The manufacturer's description is here:
7 Hook/ Safety Cutter | Benchmade
Consider this Benchmade 7hook as an alternative or supplement to a knife:
Benchmade 7 Rescue Hook Strap Cutter X15-TN Steel 4.3" Overall, Black Sheath, Orange Handle Model 7H20W - Knifecenter.com
This particular model is made of a corrosion-resistant alloy, and that seller has about the best price I've seen. I was pointed to them by someone else here on SB.
Comes with a pretty secure sheath system. The manufacturer's description is here:
7 Hook/ Safety Cutter | Benchmade