Wrestling.
Grab hold of his life support pack, & hold him at arm’s length.
Put him in the sunlit area of the hold, you in shadow.
Wait for the batteries that power his cooling unit to deplete.
Strap the poor bloke to an upper stage rocket (hey! it´s something you can find in the cargo hold, isn´t it?) and fire it; he won`t get back for revenge… 
Yeah, you’re right that probably is the best tactitc.
However, the short answer is: don’t. Its way too hard to kill or even efectively H-to-H fight someone when you ar both more or less wearing one of those “giant sumo” suits and there isn’t any gravity.