You are correct, nonnie. I suppose I never really noticed Arthur taking it upon himself to deal with the combative projections all on his own in that warehouse, as if compelled to do so. They didn't really need to take them on (or any of them out really) - yes, they were getting 'boxed in' but the rooftop snipers weren't really a threat tbh. They'd be hoofing it outta there in that van in a matter of minutes, regardless.
A: How are we going to reconcile them if they're so estranged?
E: Well I'm working on that, aren't I?
Arthur says 'do it faster' and then goes to take on snipers all by himself. Arthur, who can't just sit around and twiddle his thumbs while they're loading Saito up in the car. Arthur, who may have cocked up this whole job and Cobbs chances off ever getting home by missing the militarisation. Arthur, who must not only must he be blaming himself for this, but he must also be absolutely terrified and cannot, will not show it. Before, the job was a long shot. Now it's a gunshot between him and limbo and whatever horror Arthur perceives limbo to be. It's one gunshot between everyone else and limbo (purgatory? hell?) and them never coming back - or worse, coming back wrong.
Maybe Eames was being cocky and trying to get a rise out of Arthur. Maybe he was trying to distract him. Maybe it's all of the above and Eames knew Arthur enough to know he was kicking himself. What Eames did was he took a bit of the load off Arthur's shoulders with a size joke masqueraded as (valid) advice and a 'darling' and a big ol' explosion - and I think that is one of the reasons why dreamhusbands is so powerful. Because we love the 'darling' line, god knows I do, but what we really love is all the text and subtext that came before it - 'darling' didn't create the Arthur/Eames fandom - it's just another ingredient in the stew.
Eames says 'darling' and we hear 'darling' (supportive), 'darling' (derogatory), 'darling' (affectionate), 'darling' (cautionary). Their entire relationship throughout the film is laden with loaded words and unspoken words that speak to their history. And that really is the thing - Eames didn't need to be there. He didn't need to tell Arthur to 'dream bigger' in that moment. Eames, who is trying to juggle a severely shortened timeline and has as much pressure on him than anyone else, if not more, to try and play therapist to Fischer, still didn't let Arthur's snappish finger-clicking get a rise out of him. Still saw in Arthur what Arthur was feeling. And Arthur, who says 'do it faster', welcomes Eames helping him out - in fact, when he sees Eames approach, his whole body relaxes like his strings were cut. It's fucking teamwork.