I know its too far down the line for things to change, but reading the wiki on the Cataphract, devs repeatedly admitted to Cataphracts armed with bows. (nevermind that total war reminds me of them almost daily)
Imagine how cool it would be if the byz had two UUs. The cata archer being an upgrade to the EXISTING CA. similar to imp skirm or imp camel
Would effectively be something like a cross between CA and ele archers. Partly make up for the lack of bloodlines…
Rough draft :
Compared to HCA:
+30hp (make up for blood lines)
+2 dmg to spears (lack of parthian tactics)
+5 cav arm / +1 cavalry archer arm
Logistica gives +3cav arm
So a similar concept to the imperial camel upgrade , but with different draw backs compared to other FU HCA. Lower natural arm, dps vs spears and hp compared to turks HCA.
That’s not necessarily true, while roman heavy cavalry is unfortunately poorly documented, there seems to have been both heavily armored larcers and cavalry archers during the late roman empire (see e.g. https://www.youtube.com/watch?v=X1KD_LJwFZQ).
It needs some niche to be unique and useful. Your idea (harder to be countered like cataphract) seems good.
At the first glance of the post, I can’t think of a role it can fill. For example, anti-infantry, anti-archer, anti-cavalry, anti-siege, anti-building, anti-high-pierce armor, harder to be killed, lower frame delay. But there is at least 1 archer unit for each role.
Elephant archer, Genitour, genoese crossbowmen, mangudai, chu ko nu, rattan archer etc.
Longer range or faster speed (on par with Hussar) seems to be OP. Ignor pierce armor or dismount when killed like a Konnik is too OP. Perhaps just a tankier cavalry archer will be good.
I think it could fit in the tech tree if it was some kind of heavily armored anti-archer cavalry archer unit. So maybe lower DPS and mobility than standard cavalry archers, however more armor and some bonus armor against anti archer attacks. Could be cool, though I am not quite sure how viable it would be.