Gee, 10:1 kill ratios not realistic? I think some people need to read up on their classical history. It was common for the defeat of an army to cause the said army to dissolve. Saving a losing army is a recent phenomenon. As recent as 200 years ago, it was common to lose up to 50% of an army in a defeat.

For what it is worth, victors tend to come through battles with a 5-15% casualty rate.

Some battles that bear this out are Carrhae, Cannae, Zama, and Taginae.

Also, when playing on VH, I have found that when evenly matched (and not pausing) it can be very tough to hang with the AI due to their valor advantage. However, I am willing to give the AI that on a hard level. I think it would be much harder when the AI uses its generals more effectively and makes larger forces rather than the 4 and 5 unit armies it seems to love.