Merchant's medal

[trinitrotoluen]

I am confuse with this accessory's effecty. It said that medal give 10 aspd. I dont know if its 10 or 10% but both of this come wrong with my bs. It has 180aspd before wearing the ring,but only have 184aspd after gearing. Follow the scrip,if the ring was 10 aspd so it must give 10more aspd. If it was 10% so 18aspd (10% of 180 aspd) must be given. So anything is wrong at here or my knowlege about scrip was wrong?