So, don't take the following as me disagreeing, I think we agree on all the technical points, just that we may have different play styles, and I thought it may be helpful to flesh out my thinking more. I am curious to see what your thoughts are, as discussions like these often help me see hidden potential in builds.
Three things:
1. Fast and bursty can actually make hp-based (both pride-like and vigoras-like) weapons more attractive 'cos you can more easily shift when the damage occurs. If you are going pride route like my suggested use of Abou, you heal after FB; if going vigoras like your suggestion, you heal before. Note that if you have a red abilities heavy build (e.g. SSR Artemis), vigoras probably will in fact work better 'cos you usually unload most of them at start of combat when you are at full health. I usually use a buff and debuff heavy build (e.g. Tish), where more of my damage comes from burst, and it is not easy to burst at full health consistently outside of burst hour.
2. I actually have Sol (awakened actually) and ascension weapons, but I don't always use them. Light has a lot of very strong attackers, and while Sol is an extremely good utility hime, she usually gets benched or goes to sub when I don't need the cleanse or dispel and just go full DPS. Remember, for GO, potions drop reliably; emote for potion in raids or just free-ride on someone else's Andromeda heal if you don't need reliable heal.
3. Even with Sol, before awakening, it is still tough to consistently keep everyone topped off. Remember, her heal has a 6T CD, which often means you need to wait for two boss ODs before you heal again. And pre-awakening, her heal does not have the regen attached to it. That being said, I actually do use a build where I pair Sol AW with Joan and Tish, and if you time their abilities well, you can in fact keep everyone near full health most of the time and yes, it would make no sense to use Abou in that build.
A couple things here:
1. Remember you are sacrificing 13% assault to have a vigoras weapon, so at 100% assault, you are only gaining equivalent of 11% assault at full health. That is a lot, yes, but vigoras drops off non-linearly unlike pride and special attack, and you are gaining basically nothing around 80% health and losing out the entire 13% assault equivalent below half health. If you are using a non-Sol AW build, you will likely be spending a lot of time under 80% health.
2. Just curious, under what circumstances would your elemental be 50%? That sounds awfully low. The benchmark I usually use is either 110% elemental (30% soul weapon + double 40% event eidolons) or 170% elemental (soul weapon + 100% eidolon + 40% event eidolon). That would actually make your 18% elemental equivalent look even more attractive, but just barely attractive enough to want to replace the soul weapon with a vigoras weapon unless you have double 100%+ eidolons.
That is actually the same logic as my suggestion of combining Abou with a vigoras weapon. I would argue that works better with Abou than with pride weapons, because for Abou, you are sacrificing eidolon elemental for special attack, which is its own frame, separate from vigoras as well. For pride, you are sacrificing base assault for hp-dependent assault (I am assuming a base case of 9x assault weapons), which is not a good offset to vigoras. Consider the following data points (double-check my math, but I believe I have it right):
a. 9x SR assault (I will ignore elemental frame since I am keeping that constant in all scenarios here): 117% assault = 2.17 dmg
b. 1 pride and 1 vigoras, 7x assault all SR: 101% assault, 12 pride multiplier and 16 vigoras base = 2.25 dmg at 100% hp (~4% higher than base case) but from ~85% hp all the way down to zero, you are losing up to 5% dmg
c. 2 pride, 1 vigoras, 6x assault all SR: 98% assault, 24 pride multiplier and 16 vigoras base = 2.22 dmg at 100% hp AND at ~0% hp (~2% higher than base case) but between 25%-90% hp, you are losing up to 4% dmg. You need to have a very specialized build to dish out most of your dmg OUTSIDE of the 25%-90% hp range
For reference, my Abou + vigoras calculations from before used 170% elemental and 117% assault as base, and 130% elemental and 104% assault for Abou + vigoras. There, the dmg loss never exceeds 2% but the upside can go to 20% at near death. It relies on high elemental and the fact that assault, elemental, special attack and vigoras are all separate frames. If your elemental is lower and/or you are sacrificing a 100% eidolon instead of 40%, the numbers look awful, too.
Just curious, are you MLB-ing two pride or two vigoras weapons? If two vigoras, what does your light build look like? If I did my math right, you have to be pretty confident that you can consistently keep everyone above 90% hp for it to be worthwhile. Not even my Joan + Tish + Sol AW build can manage that unless I bring LT as well AND her blind lands. Do you have a lot of ascension weapons such that even Joan's regen can keep everyone healthy from regular attacks and Sol cover OD or something? I guess if you have a lot of defense accessories, that will probably help a lot, too.