Leizu's Silk vs Last Stand
Leizu's Silk (Huangdi): Human soldiers and worker-type units: +20% hit points and -10% Hack vulnerability.
Last Stand (Gonggong): Cavalry get +0.3% Hack armor and +0.3% Pierce armor for every missing 1% hit points.
Comparing just these two mythic-age techs, I think either Leizu’s Silk needs a nerf, or Last Stand needs a buff.
Gonggong specialises in ‘heroes and cavalry’; but his only cavalry tech is overshadowed by Huangdi’s generalist human soldier tech, which is similarly priced except for costing 15 more Favour.
With Last Stand, your cavalry needs to lose 33% of their HP to get the -10% hack damage reduction that Leizu’s Silk provides innately.
Editor testing produced the following results:
4 White Horse Cavalry will lose vs 5 Hoplites with either Leizu's Silk or Last Stand, but Leizu's Silk gives very slightly better results. (The remaining Hoplites are missing just a tiny bit more health)
3 Tiger Cav vs 5 Hoplites goes differently though. With Last Stand, the Tiger Cav lose this fight; but with Leizu's Silk, the Tiger Cav win this fight, since Leizu's Silk helps the dismounted Tiger Cav too.
Even vs Pierce damage, it took a group of Toxotes almost the same time to kill some White Horse Cavalry, whether they have Leizu's Silk or Last Stand. Even though Leizu's Silk doesn't provide pierce resist, the +20% HP still made it about the same.
These are both Chinese mythic-age techs, so I don't think the tech that benefits the survivability of ALL your human units should be equal, or in some cases, even better for cavalry than the tech which has the specific niche of being cavalry-only.