LGear
Secret Society BLANKET
My take on ASST T-Dolls is that they don't "fumble" so to speak. Essentially, once they've etched unto their weapon, they operate it with machine precision and efficiency without mistake. Where a human might take years to become proficient with a weapon, once a T-Doll etches with their weapon they become masters of their weapon, able to determine the weapon's state just through their senses. It's canonical that T-Dolls etched with their weapons can "feel" where their weapons are at all times even when separated from it, so I imagine that ASST T-Dolls are able to determine states like how much ammo they've consumed in the magazine, the weapon's temperature, physical state, wear and tear, etc. Basically, they become the perfect wielders of their weapon. As a consequence though they are proficient only with that weapon, and while they can use other weapons they can't use the same advantages with said weapons as the weapons they're etched with.