In the following the text in brackets <> are my comments.
To quote the "Historical Research Centre":
The Irish surname Filbin is a Connacht name, present day bearers in Ireland being found almost exclusively <It is not widely spread now> in the counties of Mayo, Galway and Sligo. The Filbin (Philbin) sept, Clanphilbin, possesses an ancient history, its chief being described in the Annals of the Four Masters in 1355 as one of the chiefs of the district then known as Sil Ammachada in east Galway. <There is a Castle Philbin there>. Later in the Composition Book of Connacht in 1585, the sept is described as having its homeland in Burrishoole, and as being a branch of the powerful Burke family <?!?!>, and in 1635 Strafford's Inquisition found the name to be among the most numerous in County Mayo.
When English became the official language of Ireland in the sixteenth century, documents such as the Fiants show us that Filbin, Philbin, or MacPhilbin as it was frequently designated, was often written (Mac)Philip. Thus, in 1659, (Mac)Philip appears as a dominant surname in Mayo, whilst the previously widespread Philbin is not mentioned at all. <!!!! English Imperialism> . Thus notes the Irish genealogical expert, Dr MacLysaght, the Bishop of Achonry, Philip Philips (d. 1787), was no doubt a MacPhilbin, as was Judge Charles Phillips (1786 - 1859).
One of the most well known of current bearers of the name in Ireland is the present bishop of Down and Connor, Dr William Philbin.
<There is also a Maggie Philbin who is a TV presenter in the UK and two brothers who played the English game of Rugby League from Wigan named Philbin. I also suspect that Philby is a derivative of our name. It is true to say, from the above text, that Filbin is the true root of a lot of "Ph(F)il" names.>
BLAZON OF ARMS: Barry wavy of six azure and argent, on a chief of the last a lion passant sable collared or. <Yes, I do not understand this either>
Source Reference: Burke's General Armoury, page 800 <I will check this...sometime>
Translation: Azure is the colour of Loyalty and Truth, whilst Argent (white) signifies Peace and Sincerity. The chief is a symbol of Dominion and Authority, whilst the lion is associated with Strength, Courage and Generosity.
CREST: An arm embowed in armour proper charged with a fleur-de-lis gold.
Translation: The arm denotes Power and the fleur-de-lis is a token of Faith, Wisdom and Valour.
MOTTO: Deus, Patria, Rex.
Translation: God, Country, King.