Some thoughts to share. Speaking in terms of ergonomics, not the old b.s. about taking a knife to a gun fight.
1. watch some youtube street fights. The participants usually try to hit a person's face, try to use bulk in vertical wrestling. They tire easily.
2. if you have trained in knife fighting against another person who has a knife, you will experience an overwhelming immediate tiredness that will hit faster than what you see in a youtube video.
3. you lose much of the value of martial training when you attempt to engage malo a malo.
4. Before you practice knife fighting, practice non engagement. Find a video on youtube that teaches movement to one side or the other of your opponent so that he cannot strike you. This is called "shooting". How effective is this? Example. Most people are taught that if they are held at gun point, to bend backwards (called rocking), draw and shoot static (and be killed). I had a master show me what to do. He shot by me, drew as he took off, and had a "shot" into me before I could react. When you think this b.s., a classmate was being held up at gunpoint at gas station locally by a bad guy. He moved, drew and killed his assailant. He had been trained in OOda Loop. Try looking up san soo. Weeks are spent at the basic level avoiding contact.
5. This is how easy knife fighing itself can be. You can only do about 8 movements ergonomically. Nearly all are slashing movements, down, up, or to the side to side across the body. A couple of moves are stabbing. I don't like stabbing as the shock of the contract goes right back into you - so daggers are largely out in fighting. Moreover, stabbing requires you to balance and move forward instead potentially keeping a balance in slashing which allows you to move in any direction.
6. Just study a youtube basic escrima video on the 8 or 9 basic movements and practice them.
7. I can no longer do what I used be able to do. Example. A person holding an axe handle or fake knife over his head. On the whistle, he tries as fast as he can to bring down the object and strike you on a clavicle. You, as the victim, were expected to take the object away from the aggressor, in motion, and stab him in the ribs. I can not do that any longer. I can, however, practice moving my arms and body to keep them limber. That is all you have to do. You don't need a black belt to do that. Your opponent has probably not had any martial arts training.