One of my air hoses developed a split near one end. It’d be good as new with a replacement fitting and new ferrule. The parts are cheap as chips, but the crimper’s more than I can justify to fix a $25 hose. Don’t suppose we have one floating around the shop somewhere?
Most of the ones I’ve found (that aren’t huge and/or hydraulic) look something like this: https://www.homedepot.com/p/Milton-Industries-Inc-Hose-Ferrule-Crimping-Tool-1626/301836727
Have you considered a regular hose clamp at the fitting? you could use a little epoxy or jb weld (if you have them on hand) for a better seal, tighten the clamp and then use electrical tape to cover the clamp so it doesn’t get caught with cords or other stuff as you use it. If it was accidental it should fix it or be worth fixing. In my experience, if the leak is because of the age of the hose once you fix it, will continue to develop leaks as the material is starting to break down. Good luck!
a hose clamp actually works wonderfully. I needed a long3er air hose at the shop to complete the 3d printer cabinet as the one hanging from the ceiling wouldn’t reach. I found an air hose in the back with one end sliced off. I shoved the barbed fitting into the hose and put a hose clamp on it and good as new.
A hose clamp is my backup plan. A crimped ferrule would just look so professional 
Good point about the age. The rest of the host looks good so far (knock on wood) but I agree it’s probably in the downhill slide of its useful life.
I have one your more than welcome to.
I just noticed I never concluded this thread.
@jamesfreeman I didn’t borrow your crimper because @JOSEGAYTAN was right about material breakdown. I put a hose clamp on a temporary fitting, and I’ve had to keep shortening the hose from both ends as they disintegrate.