It's in magic.lgp, no wait I guess these are loose tex files in battle. But textures aren't there as a complete texture and is cut into pieces.
Could not find the textures for Cloud's normal slash attack but I was able to find most of the other ones... There's a file called cloud1.tex or something like that but Biturn can't open it, also every other file uses the Japanese names so I'm not even sure if that's it.
Clouds slash effect is in seffect3. Fourth and fifth lines. Its all split apart.
Is that in magic.lgp? Because I don't see that file.
It's a loose file in the battle folder.