Cavalry and chariots against infantry

[Domen]

But I generally think archery, and missile weapons generally, were important.

Yes. But their lethality against armored troops was not as high as is sometimes imagined.

Anyway - for example at Carrhae, according to some theories (see the article below) Surena's troops were using special bows and special arrows (with arrowheads of improved penetration capabilities), and that's why they were so efficient (also firing from close range added to this effect):

http://www.casematepublishing.com/dlc/97...033892.pdf

I'm not sure how valid are theories from this article (maybe You guys can tell), but if the author is right - then Parthian bows and arrows at Carrhae were indeed "special", while in other battles they were much less efficient when it comes to penetrating Roman armors and shields.