Sir Saher de Quincy is believed to have borne the above arms:
Or a fess gules a file of eight points azure.
Reed M. W. Wurts, who is considered an authority, gives this as Sir Saher's arms at The Magna Charta Barons at Runnymede Home Page
The Baronial Order of Magna Charta gives the above arms for Sir Saher de Quincy:
Or a fess gules a file of eight points argent
The BOMC, founded in 1898 is definitely an authority. Sir Saher de Quincy, 1st Earl of Winchester, Magna Carta Surety Baron 1215; he lived circa 1150-1219.
The coat of arms directly above may or may not the arms for the Magna Charta Baron Sir Saher de Quincy, but they are found in many rolls of arms for the de Quincy surname: gules seven mascules Or. They are found in one instance with his wife. The most knowledgeable sources I can find do not credit him with these arms. Some believe that Sir Quincy adopted these arms later in his life and the other arms were his in his youth. I'm not even an amateur herald and can not possibly say. The arms directly above did belong to other de Quincys, and these have been adopted by many family tree enthusiasts for Sir Saher (sometimes written Saer).
People who spend their lives studying arms and titles and the rules governing them, may be officially recognized as heralds. Even heralds, recognized as experts in this field, may disagree on fine points of heraldry. There are a few basic rules, however, that can be understood by those of us who are enthusiasts but not experts.
The rule I would begin with is that arms are for a specific individual. Only consider - a knight on the field of battle with his armor and helm concealing his features was identified by the arms on his shield, on his banners and pennants, on the caparisons on his horse, and by his sleeveless coat depicting his arms, (by which we have the term 'coat of arms').
What knight would want his feats of valor to be credited to someone else? What knight would want someone else to carry his personal insignia - suppose they were cowardly and fled the battle? It is not difficult to see that practical concerns required knightly arms to be personal.
A device such as a label (shown in an earlier post) would be removed from the shield, coat, pennants, etc. of the eldest son when he inherited the full honors of his father's title - that is, when his father died.
In certain instances, a young knight might adopt the arms which had belonged to his grandfather, perhaps with the permission of his mother if she were the only surviving heir of her father. Arms could signify what place a man held in his family: whether he was the 'son and heir', or a younger brother, or a cousin.
Sons did not always adopt the coat of arms that was borne by their fathers. Sir Gilbert Segrave carried a shield with three silver wheat sheaves on a black ground. His son Nicholas kept the family colors but changed to a silver lion rampant on a black ground.
Certain devices were added to the shield signifying honors won at specific battles. The arms a knight carried were a sign of his authority, accomplishments, lands, power and wealth.
We cannot claim these arms of our ancestors, any more than we can claim the honors and lands they once held. We can take note of them and study to understand the meaning and symbolism, and we can make an effort to discern which arms belonged to which ancestor.