My opinion is likely to be a part of small, minority view, but both of the models shown use a plain second hand, which I believe to be a weakness of design. Part of my objection to that choice is aesthetic, and part of it is practical.
Aesthetically, I find that some kind of accentuation of the tip of the second hand makes the dial more interesting, and is more consistent is terms of balance with the typically large indexes, and hour and minute hands found on vintage dive watches. A thin second hand, shared with the most elegant and refined dress watches of the day, strikes me as being out of place.
Practically, while of course only a small fraction of such watches were actually used for diving, there was at least a serious pretense that they were designed to be high performance tool watches. As such, there was good reason for the indexes, hour and minute hands to be large, and luminescent. So again, it strikes me as dissonant to find a second hand – a hand that could literally prove critical to a diver – to be both thin and entirely unadorned.
To my mind, the designers of the IWC ref. 1812 Aquatimer got it right (and there were others, of course). The luminous "paddle" on the second hand (also a feature of the ref. 866 Ingenieurs) would have allowed a diver to quickly focus on the seconds if necessary, and even under adverse conditions (e.g. challenging light).
Regards,
Tony C,.