Your client is looking for spriteÀΰ£Á·µµµÏµµµÏ_³²_īŸ¸£_īŸ¸£_°Ë±¤ , which means :
For the male (³²) thief (µµµÏ) class, for the weapon sprite (_īŸ¸£_īŸ¸£, which is view ID 16 - WEAPONTYPE_CATARRH), for the weapon trail sprite (_°Ë±¤).
Basically, one of your katar weapon is usable by the thief class (normally they're only usable by assassin or assassin cross classes, so I'm assuming you've changed the applicable job field xD). The trail sprite is missing (it is usually required for the default weapon types). For example, the weapon sprite :
The trail sprite :
I'm not sure when this is actually displayed ingame though... anyway, you can create empty act/spr files and it will fix the issue. Good luck!