saved soldiers come in two flavours. the ones at the base, and the ones in the battle.
the saved loadouts are on the ones in the base. search for the battle section, it has all the tiles (saved in binary), all the items, and all the units in the battle. honestly though, manipulating that data is not recommended unless you know _exactly_ what you're doing.
i'd suggest instead, simply bump up the unit in question's time units and energy to an absurd level so that they can go pick up whatever item it is and get back in position, let the engine handle it, then re-edit the time units back to their original values. much less margin for error that way.