"These honourable Accessories [supporters] of the Heraldic Shield are said to have been introduced, (like Quartering) by Edward III, but they are of uncertain authority until the reign of Henry VI." (Boutell, Charles., A Manual of Heraldry, p123)
What does mean "authority" in the above sentence? At first, I thought it alludes to citations of references but it is meaningless in historical point of view. is it possible it means importance in there?
There is another similar sentence:
"A lion and an antelope, and sometimes an antelope and a swan, have been assigned to Henry IV. and Henry V., but upon no very reliable authority." (Clark, Hugh., An Introduction to Heraldry, p67)