You know, it's quite easy to have a 'tank' pegasus knight that isn't a dodging speedster.  The system has the same stat cap of 30 for all stats once everyone promotes, so differentiation is entirely dependent on growth rates.  Perhaps Aurelia could be built like a wyvern rider in this case?  If she's going to go for being a front-line unit it would certainly help to have some defense, as strange as it might be for a pegasus knight.