The computer in my arm is more powerful than every system, on any sub light speed capable world, combined. It runs quite well without her, she simply rests in it when she's not in the real world. She and I talk while she's in there. It facilitates the communication quite well.

As for the flaw... putting your life in the hands of something you can't recognize the stress you're putting on it. Combat is inherently stressful. If not carefully tended to, combatants do not get stronger. They get more volatile.