These are still early days for head-worn mixed reality. For now, if you want to manipulate objects in MR, you pretty much have two choices: either bare hands or VR controllers.
But this goes against many centuries of human wisdom. In our everyday life, we have pens, brushes, hammers and chisels, screwdrivers and pliers. Humans have developed many specialized tools that amplify both the power and the precision of our hands.
I suspect that sometime soon, the act of picking up an ordinary pen to make a magic animated scribble while wearing your mixed reality glasses will become commonplace. We are not there yet, but with any luck we will be soon.