Sounds a bit like a mutual reception would balance that out; they're different from one-in-its-dignity-the-other-not, of course, but the general idea is that the rulership is almost 'exchanged'. That is actually one of the very cool things about his and my synastry, which, I think, tops the karmic soulmate's. There are so many amazing, yet subtle, hidden connexions.
There's a rather fascinating, and deeply nuanced relationship between Aries MOON and Libra SUN I'd never considered before until this. The Aries MOON embodies Martian qualities with lunar receptivity; it's a curious balance. The Libra SUN, on the other hand, marries the energies of Venus and the solar fire. Between these two points, there's an odd mutuality and resonance, so when they're in an actual opposition, it can create a powerful balance between them, rather than the standard thought of 'opposition'.
I wasn't quite able to determine the appropriate 'complement' to VENUS in Leo, however; though, its mirror is SUN in Libra, curiously enough, as both carry solar / Venusian energy.
This is an example of mutual reception, but in synastry. It's a powerful resonance.
I say I'm having trouble with the appropriate complement for VENUS in Leo, because it seems, logically, that it would be MOON in Aries -- which brings us right back to the beginning. I'm not saying I don't like it -- Martian / lunar energy, and Venusian / solar energy -- it's lovely! But I prefer the Venusian / solar energy to be embodied in the Libra SUN when 'paired' with the Aries MOON. 'Paired'; like a fine wine with a gourmet meal.
In response to your question, however, there might be something to that, given the fact that -- as you've said -- MARS is in its rulership in Aries, while VENUS is in its detriment; in other words -- it ain't happy in the sign of war, sex, anger, and impulsivity. Conversely so for MARS in Libra. It can feel a bit 'hindered', as it's the natural domain of VENUS, and not MARS.
Now, would this mean, in the case of a conjunction, that the one whose experiencing placement in its ruler that it'd be 'more felt' ? I ... don't think so. Perhaps a bit more easily expressed, however. It'd seem 'more natural' to it.
That's why I think synastric complements could be a hidden boon, in the case of placements which are having a bit of trouble, perhaps, due to being in detriment or fall. The SUN, for example, is in its fall in Libra, due to the equinox connexion. The MOON doesn't have the easiest time in Aries, but it's neither in its fall nor detriment. My 'falling SUN' may appreciate the synergistic complement that his Aries MOON provides. Sometimes 'no news' is good news, heh!
At any rate, complements are fascinating. Mutual receptions are some of my favourite things to study; lately, however, I'm really getting a kick out of finding how these energies interconnect and balance through natural complement.