After watching Gundam SEED and how they talked about an MS's OS, I stared thinking, why do you only have to have one OS, a VF or an MS is pretty complicated. Maybe they have multiple OS, a simple one for regular fighting (like if the pilot was playing Armored Core) and a more complicated one for when you have to pick something up. On the combat OS pulling the trigger on one of the sticks would fire your gun, but if you switch to the fine movement OS the harder you squeeze the trigger or the stick itself the more the hand closes.