Help with texture transparency

[Iwvi]

I need help with the transparency of a texture. Well, to be more precise with pit's swords, the inner part that looks purple, i want to make it semi-transparent. But, I know that the CMPR format used by his bow/swords does not support semi transparency, so my question is if there is a way to make it semi transparent by changing the texture format? if so, how can i change it, I tried brawlbox but in game it still looked opaque. Is there a way to change the format? even if it requires hex, I would aprreciate any help