These tended to be extremely simple and concrete. A color might be added to describe a person's hair or complexion. Maine with the red hair might be called Maine Ruad. Little Lugaid might be called Lugaid Beag. Cathan, who is clever like a fox, might be called Cathan Sinnach.
Locative names state that someone is from a particular place.
To form one of these types of byname properly requires a knowledge of Irish Gaelic. If you want something like this, do the best you can and allow for changes on the name submission form. Better still, ask that your name be corrected if necessary. One type of byname that we have not been able to document is a second, unadorned given name. Likewise, if you want to use Cernach and Eoin, use Cernach mac Eoin rather than Cernach Eoin.