I hope the following is of interest..apologies if its too long - unfortunately, while my father is from Ballinrobe, I've never lived there - but of course thats where a lot of my relations are.
The surname Feerick is not that common in Ireland – its very geographically specific to County Mayo, particularly to the town of Ballinrobe.
The name is believed to be derived from McPheorais, which is “son of Piers” (often referred to as Peter) in Gaelic. “Mc” or “Mac” means “son of” – hence the number of Macs in Ireland and in other Gaelic countries like Scotland. In Gaelic, the name Feerick is MacPhiaraic, or NicPhiaraic for the ladies. The Piers referred to was Piers de Bermingham, who was an Anglo-Norman knight (from the ruling family of the city of Birmingham in England) who helped conquer Connacht (roughly western Ireland) for the Normans and was awarded the Barony of Athenry in County Galway. So it would appear that commonality of the name Peter among the Feericks of today stems from Piers and the naming of sons after their fathers and grandfathers.
In the 1500/1600, the surnames became more specific. During the reformation, the more Catholic/Irish side became Feerick and those who wished to be more acceptable to the English kept the name Bermingham. Some converted to Protestantism, many did not. Remaining Catholic carried a heavy burden because for many years Catholics couldn’t own land in Ireland or practice their faith without persecution.It is believed that during this time, the Feerick part of the clan was forced from Athenry and moved north to the poorer land of South Mayo – in or around Lough Mask and the town of Ballinrobe.
As to why the name did not spread throughout Ireland is much to do with Ireland’s recent history. In poor economic times, it made little sense to move from one part of Ireland to another, so as with very many families from the West of Ireland, members of the Feerick clan emigrated to the US and to Britain. It’s only in the last 20 years or so that Feerick has appeared in other parts of the country, though many of course had emigrated from Mayo to Britain and to the US throughout the 1900s. I can recall in the early 1970s that according to the phone book, there were no Feericks living in Dublin, and only three families outside of Ballinrobe.