okay so here's the brief explanation regards that stuff in assassin weapon sprite folder here's the pattern by default
1.î¼¼½Å_¿©_´Ü°Ë_´Ü°Ë.spr Dagger, Dagger (Female) 2.¾î¼¼½Å_¿©_´Ü°Ë_°Ë.spr Dagger, Sword (Female) 3.¾î¼¼½Å_¿©_´Ü°Ë_µµ³¢.spr Dagger, Axe (Female) 4.¾î¼¼½Å_¿©_°Ë_°Ë.spr Sword, Sword (Female) 5.¾î¼¼½Å_¿©_°Ë_µµ³¢.spr Sword, Axe (Female) 6.¾î¼¼½Å_¿©_µµ³¢_µµ³¢.spr Axe, Axe (Female)
in this case those 1-6 are default sprite you can see it inside the data/sdata/rdata grfs but here's how it works let say you have custom sword1 and custom sword 2 when you wield it both it will show the #4 default sprites. you can change the 1-6 depends on your desire. To me on my server i disable all axe weapon to worn by assassin job so that i can use the (#6 axe-axe sprite) and i edited it because i made a custom weapon Sange & Yasha as axe type weapon see the link of the picture here
Hope you understand and there's no way you can add custom wield except you replace the weapon as a katar lol