The Blues were pushed all the way by a dogged Moneys team, who play two division below them in the women's pyramid, eventually running out 3-1 shoot-out winners after it had ended 0-0 after normal time at Westleigh Park.
Boss Sadler praised Moneyfields' strong showing in the PDFA Women's Cup showpiece - yet he felt his side failed to 'get out of first gear' in the final.
Still, Ava Rowbotham's winning penalty - after Hannah Haughton had saved from Kim Whitcombe, while Carla Nicholson and Roxy Lee-Stewart both missed from the spot - ensured Pompey picked up a third trophy of the season.
And despite his disappointment with the Blues’ showing in the final, Sadler was just relieved they came through eventually to retain the PDFA Women's Cup crown they beat Moneyfields to win back in October.
‘I'm pleased with winning at the end of the game - I don't think we came out of first gear - huge credit to Moneyfields because I thought they played really well,’ Sadler admitted.
'They caused a few problems early on and sat into a deeper block in the second half and we couldn't break them down.
‘We were disappointing today from a performance point of view - we've got to learn now as a group that the season is not over and you can get highs like the Southampton one.
‘They're (Moneyfields) team on the up and a team who wanted to dethrone us. They left everything out on the pitch, whereas I thought we had two, three or four gears left in us.’