Nope, there are only 2 frames even if I download it once again.
Thank you for being so quick in your answers !
Edit: I found something, every file except arms_grenade and arms_knife are animated with only 2 frames.
There are 150 framesb ut only 2 keys.It doesn't work if I drag the last key to the end.
It won't make a difference. I tested the 2 files, the unity project and the separate files, and both worked normally when I exported from blender. I also tried exporting them again and when I opened them they were working the same. I really don't know what's going on in your case. Unfortunately I can't help you. Sorry.