[Nick_K]

There are a few other units like this - in particular the atlanteans. However, it would be quite a big change and it's rare that units would grow old enough for their growth to have an effect.
In fact, the only way it could happen in a dominions game time scale is through 'decay' or similar aging magic. One could say that this sort of death magic is different from 'natural' aging in that it provides the deterioration of age, but not any growth or increase in power.