Maybe we can work that out, as we go. Maybe she saw the little one and decided she had to be at his side at all times, particularly when his parents died and left the fortune to him?
Maybe that explains some of the firecracker-ness too. Like she won't stand anyone getting too close to the young master, as he is hers and she won't let anyone touch him. ^^? Maybe there's some selfishness in it too, like she wants him all to herself, as her little cuddle toy?
That... Is... Brilliant! After all, the shield is still used as a weapon. (The Meister customises it, often, and so it gains things like blades, which spin like a buzzsaw. He also uses it as a hover disc, a bit like Kid's skateboard.) And since he's rich, as you've suggested, he's got the resources for it. ^0^