What can we say? Strange things happen in software development. That's no excuse, but we are now clearing up the problem.
Firstly, we'd like to thank players for finding this issue in Rome: Total War. We've calculated that the community has now spent 17,000+ man years in playing RTW. Unfortunately, we don't have the resources to match the dedication of our players so we hope you can forgive us for the lapse in not spotting this bug, which was introduced late in the project. We're less than happy that we missed it. Even if we'd put everyone involved on the project into testing (and stopped putting any cool stuff in the game) it would have taken about 300 years to match your efforts, and we're pretty sure that most people wouldn't have wanted to wait for 300 years for the game to be published.
We've now addressed the problem. In the current build units now use their secondary weapon values where appropriate. Archers and skirmishers, for example, now 'know' to use their knife or shortsword combat values instead of their missile values. The main results of the fix is that some missile troops won't be as effective in hand to hand combat, and lance armed cavalry will be more effective than is currently the case after their initial charge. We're now playtesting to make sure that unit balancing hasn't been affected in any overtly strange ways and that combat results are what we'd exect them to be. You'll be happy to know that so far, so good...
This late change does mean that other patch elements have to be retested. As a result, the patch has been slightly delayed and won't be available when we expected. But, having monitored the forums, we know that this is an issue that needs to be addressed. We also know that you're eager for the patch. We are too, but we want to do the job *properly*. That's going to take slightly longer than we thought it would.
So thanks for your continued patience. In the meantime, the game still works and is extremely playable. Once the patch is out you'll find that is even better.