Matk for items is added in differently from the RR emulator (if that was merged here). Use a : in the ATK field as seen below:
1601,Rod,Rod,4,50,,400,15:30,,1,3,0x00818315,7,2,2,1,1,1,10,{},{},{}
15:30
15 = Attack of the weapon
30 = Matk of the weapon.
Per the item_db_re.txt file from the rA SVN: https://rathena.svn..../item_db_re.txt