After much more experimentation, I've manage a very slight improvement in the writing animation, and also of course added a simple rigged pen to follow the motion (though this is probably not the pen I'll use in the production shot). I didn't want the pen to look too mechanical. A person writes mostly with the wrist (or fingers -- but when writing large letters like this, the wrist motion dominates). So while the point of the pen follows the text, the top of the pen moves less. I rigged this with two separate animated curve paths in Blender, using bone constraints to get the pen to follow them. I'm hoping this will be easy to integrated with the IK rigging of the character.

(No sound).