In the ARM History output, that's just the ARM setting, NOT the radio power. ARM can say it's putting the radio at 24 or 30 or 127, doesn't mean the radio actually goes to that amount.
The ones to watch are in your GUI short or in the show ap bss-table, that shows you what the radio is actually set to. You can also capture the output of 'show log driver | include Power' and you will see just what the AP is setting. Copy of my output is below.
215-livingroom# show log driver | include Power
[ 132.227810] Mon Dec 14 00:57:12 2015:223 26.186026 wifi1: EIRP (Config: 24.0dBm, Set: 23.0dBm, AP Max: 23.0dBm, Reg Max: 27.0dBm), Conducted Power Set: 18.0dBm, Gain: 5.0
132 24.965199 wifi0: EIRP (Config: 24.0dBm, Set: 23.0dBm, AP Max: 23.0dBm, Reg Max: 27.0dBm), Conducted Power Set: 18.0dBm, Gain: 5.0
223 26.186026 wifi1: EIRP (Config: 24.0dBm, Set: 23.0dBm, AP Max: 23.0dBm, Reg Max: 27.0dBm), Conducted Power Set: 18.0dBm, Gain: 5.0
215-livingroom#
You should see something like this in your last line:
wifi1: EIRP (Config: 24.0dBm, Set: 22.0dBm, AP Max: 23.0dBm, Reg Max: 22.0dBm), Conducted Power Set: 17.0dBm, Gain: 5.0