Trusting in God Persevere

I bought a key chain in Belfast (which I still use) with the Keenan coat of arms. It says the following on the back about the origins of the name Keenan:

This is the anglicised version of the Gaelic MacFhionnain meaning "son of Fhionnain" from "Fionn" meaning "fair". The census of 1659 lists the variant MacKeenan as a principla name in the barony of Ardee, Co. Louth. Some were historians to the MacGuires of Fermanagh between 1345 and 1508. The motto for Keenan is "Trusting in God persevere".

I don't know much faith to put in this, since it is a key chain from a tourist spot in Belfast (where we found info on a fantastic black cab tour). But then again, it does seem to track pretty closely to something else my uncle found. And I like the idea that we were historians.