There is/was a Bridson coat of arms, and more than one version, but I believe that it is no longer registered as such. Try looking in older editions of Fox Davies Armorial Families under Brydson. There is also a reference to it in Moore's 'Old Manx Families' under The Bridsons of Ballavervane although I suspect that he attributed it to the wrong branch. The motto was Tutus in Undis (Safe in the Waves) which didn't stop a Hugh Bridson from being drowned at sea!.
Michael Bridson