Tell us about yourself!
If she is a normal sized three year old, a fleece throw might do the trick, as those are fairly small and cheap.
Indeed. I think what gets most people is the truly alien shape of the weapon. Many also make fun of the limited reach of the Bat'leth. However, you really don't need reach with this kind of weapon. The way you hold it in combat means that any frontal attack will be blocked with very little effort on your part. With such a sharp and heavy sword, the slightest movement can do great damage to an attacker.
Can the Pi run Netflix from the right browser? That would be a nice addition to a device like this.
One day I want to do this with an less old console TV. Like this one. That would be awesome.