Right now the game feels fine. I feel like it'd get a mostly positive on steam in its current state. Can get a little repetitive.
I feel like a lot of this can be mitigated where there's a lot of room for action/change. One of these is the dagger. My suggestion is the dagger is a lot more of a vehicle, and not something you wait for only to be put in a loading screen. I guess to be more direct with it, yk that cutscene of the harpoon being shot at the train when you arrive? Allow us to actually do that. Maybe you are about to extract but your friend wants to keep looting for a bit; make it so you can go call your dagger and drive it alongside the train, defending it from any potential raiders while you wait for your friend to jump down to extract. There's such a heavy emphasis on the dagger and it's point in the game, but yet I feel like its nothing more than some random spot in the void with some animations.
TL;DR: Allow us to PLAY more in regards to the dagger itself, not just use it as a crafting station and loading screen,