With the slight addition that EIRP is what comes out of the antenna's, so that includes the 'antenna gain' which seems to be 3.5 dBi for 2.4GHz, and 4.5 dBi on 5GHz..
So what comes out of the radio (assuming zero loss in the connection between the radio and the antenna), is 11.5 dBm (14 mW) for 2.4 GHz and 10.5 dBm (11 mW) for 5 GHz.; with a setting of 15 dBm in your AP or controller for the AP-225.
In Aruba products you typically set the EIRP value, the amount of radio output power is internally derived from EIRP.
Herman
#AP225