What kind of action is this? Is it really just a half action to retrieve a disarmed weapon?

In my games I have it as a full action. It is not as easy as readying a holstered weapon after all. They have to bend down, grab the item, stand back up and get it into the ready position to defend themselves again. Essentially I have it as the stand action and the ready action together. I have also had GMs that wanted you to spend a half action looking for it as well, but It doesn't make sense to me that everyone would not just pay attention to where their weapon went, so as long as they are immediately picking it up again, I don't have them do that.

If the PC is not in melee or being directly shot at (e.g. in cover) I usually allow them to retrieve the weapon/item with a half action.

It still carries risk because if an enemy is using suppressive fire, there is a small chance they'll get hit (I roll for that if that is case).

If they are in melee or are being shot at directly, I'll allow it for a full action and should the circumstances dictate it, allow them to perform a skill/characteristic test to reduce it to a half action.