What's the point of summoning back his arm and leg if he still has that big hole in his chest?
The treasured 'object' (romaji mono) could be anything since 'mono' can apply even to person (it is a very broad term). 大切 'taisetsu" can also mean intimate (as in very close in relationship). If he brings back his dad, that would really be ridiculous. So throughout the series, shouldn't we have already learnt what is Ed's treasured object already? Something is wrong here. AH, I got it. Al's body.
Also it could also be thought of that the clanging of his two arms is Ed's last gasp action, his final act against Dante and gang before he dies.
So Ed dies, Al lives restored to full.