I saw in the recent SoT news video, armory boxes will be locked when using it from another crews ship, which I think is fair after adding the harpoon gun. But I do feel like fights will be entirely one sided, only being able to use one weapon. All weapons have counters, and being able to change your playstyle on the go is often required when fighting larger crews to account for their weapon variety. A one on one fight might be okay, but when you're forced to pick between long range and short range, it will be very one-sided when fighting large crews with more variety of weapons. I think a solution to this, would be to lock the armory box, but once the ship is taken control of, either by sneaking on or killing the crew, you should be able to lockpick/shoot the lock on the armory box and then swap your weapons from there.
I think the action of lockpicking should make an slight audible sound to let the crew know there is someone trying to open the armory box.
I also think it would make sense for the enemy crew to be able to relock the armory box if the lock is removed.
This change would make choosing the harpoon gun stay a strategic decision while making it rewarding for being able to successfully board with it.