The entire process is explained in the video. (https://youtu.be/HC-GMMuSBwk)
To assemble the dagger pieces lay them out with baruka_dagger_0 as the tip and baruka_dagger_8 as the end of the handle. Pieces 3, 6, 7, and 8 are all printed upside down, because they sit better that way, so flip those while you're assembling it. The shape of the dagger is pretty distinctive so it should be pretty obvious if the pieces get flipped around.
Sorry about the small gap in the middle of baruka_dagger_5. It was the most challenging piece for me to model and there are a few things I could have done better with it. I didn't notice the gap in the print and completely forgot about it until I was uploading the files. If you're sanding it and using wood filler like I did I doubt you'll even notice.
