A search of Upper Canada Land Petitions can be found at the Library and Archives of Canada website; occasionally affadavits about War of 1812 service can be found among some of the petition papers.
"C," Bundle 5
22 April 1850
Peter Ruttan affidavit vouching for the late Captain James Cotter
Isaac Frazer, late lieutenant, Militia Dragoons, On Duty in 1812
THE UPPER CANADIAN MILITIA.MIDLAND DISTRICT (Continued.)Lieutenant Henry Davey.Ensign John C. Clark.TROOP OF DRAGOONS.Captain Christopher Fralick.Lieutenant John Fraser.