Teioh edits kernel2.bin, which contains text data. The fact that Teioh is a text editing program should make it obvious that you cannot edit anything other than text.
What you want to do is edit weapon stats and properties, which is stored in kernel.bin, which you need to edit with a hex editor. And no, it's not easy.
This can all be found out by searching this forum. Do so for any other questions because the answers are easy to attain.