Version 2:  Updated scabbard so side hook is thicker and less prone to breaking.

With specs provided by a 10 year old who likes to play ninjas, spies, etc., I designed this to be a little safer than most daggers available.  This dagger has a blunt tip and rounded edges.  The scabbard that holds the dagger can hang from a belt or pants at the waist.  For ergonomics, the belt clip is at an angle with a mirror image version so a scabbard can be worn on each side.

Everything prints without supports.  The blade/hilt prints vertically with the hilt providing enough support on the printer.  The handle prints separately also vertically.  There is also a small key to print which is used to align the blade/hilt and handle when gluing together.  When printing the blade/hilt, I added a filament change during the print so the hilt can be printed a different color from the blade.  Left and right scabbard versions also print vertically without supports.

I printed everything at 0.2mm and 15% infill.