Arms awarded by King Charles VII of France in 1427 to Sir John Stewart (c.1365-1429) of Darnley, 1st Seigneur d'Aubigny, 1st Seigneur de Concressault and 1st Comte d'Évreux, Constable of the Scottish Army in France. To quarter Stewart of Darnley. This was called "the glorious privilege of quartering the royal arms of France with his paternal arms". 
Text of grant (translated):
Quartering as ordered by the grant of King Charles VII of France, with the arms of France in the 1st &amp; 4th quarters of greatest honour and with Stewart in the lesser 2nd &amp; 3rd positionsTo the same our cousin for the causes and considerations before mentioned in augmentation and increase of honour for him, by posterity and house; and to the end that his said services may be for ever remembered in this oar Realme and elsewhere, and that his descendants may by this our favour be indyned, tyed, and obliged to us and the house and Crowne of France, Wee have of our certain knowledge and deliberate purpose, and by advice and deliberation thereupon had with those of our blood and Councell now present with us granted and doe grant, &amp;c.. That he may have and bear for ever in his Armes, Escocheons of France, that is to say in the first and last quarters thereof in each 3 flowers de Lys of Gold, in a field azure so and in such forme and manner as the same is here poartrayed, depicted and blazoned. Willing and granting that this our pretent gift, grace and grante may by him and his detcendants who ought to weare his said Armes be enjoyed and used from time to time for ever, &amp;c. And for a more full confirmation of these pretents, wee will that the same be registered in the Chamber of our Accomptt and at the Treasury of our Chancery &amp;c. Given at Blois in the month of February in the year of Grace one thousand four hundred twenty and seaven in the tilth year of our reigne.The arms henceforth borne by the Stuarts of Darnley and Aubigny were, Quarterly 1st and 4th, Azure, three fleurs de lis or, within a bordure gules charged with eight buckles or, 2nd and 3rd Or, a fesse chequy azure and argent, to which last coat at a later period a bordure engrailed gules was added. The Stuarts of Aubigny afterwards added to this shield the arms of Lenox as a surtout. Argent, a 
saltire between four roses gules. The well-known crest of the Stuarts of Lenox, a bull's head breathing flames was used by Sir John Stuart, and his war-cry Avant Darnley became afterwards the motto of the family. 
The residence of the Stewart family in France was the Château d'Aubigny, Aubigny-sur-Nère, Berry. Compare arms of Duc de Berry
(Source: Cust, Lady Elizabeth, Some Account of the Stuarts of Aubigny, in France, London, 1891, pp.12-14[1].

The buckles were the canting arms of the de Bonkyll family of Bonkyll Castle in Scotland, whose heirs were the Stewarts of Bonkyll, a junior branch of which was Stewart of Darnley. (Source: Gaspard Thaumas de la Thaumassiere, Histoire de Berry, Paris, 1689, p.698[2])
Own work, using buckle from  File:Blason Gabriel de la Vallée.svg by User:Spedona
Lobsterthermidor (talk) 02:42, 20 February 2020 (UTC)