The names of the known companions are no more than fifteen from 'unimpeachable sources', (with six names added by more recent historians studying the best secondary sources). Twenty-one out of over five-thousand isn't much, but then, it was nearly a thousand years ago, plus the natural confusion in the aftermath of a major battle and years spent subduing the countryside.
So I find it quite amazing that Leo and I are both directly descended from six of the companions of William the Conqueror, from the list of fifteen; Leo alone is descended from a seventh companion.
Here is a link to the coat of arms for one of them - Walter Giffard. It is an excellent website with the symbolic meaning of the colors and charges on the shields, and some history of the person.
Blazon: gules three lions passant gardant in pale argent
Described in the classic The general armory of England, Scotland, Ireland, and wales: by Sir Bernard Burke, copyright 1864, are the arms of Walter Giffard, Seigneur de Longueville, circa 1015-1085. He received fame for his valor at the seige of Barbastro in Aragon, Spain, part of the Reconquista. Sir Walter Giffard is a direct ancestor of both Leo and April.
Some of the early known rolls of arms I have found for England begin circa 1270-1280. The Bayeux Tapestry, woven soon after the Battle of Hastings (1066) shows some arms on shields, so we know that at least some arms were displayed as early as 1066.
About 1245, a monk called Matthew of Paris wrote and drew pictures of some of the arms borne by the great men of his time and prior to his time. Here is a link to digitized parchment image, courtesy of the British Library. I am still searching the pages for the shield of Walter Giffard.
[A slight detour here, just because it is so fabulous to have the only copy of Matthew Paris' "Historia Anglorum" available on the Internet!] The link opens to the page recording the crowning of King Henry III (age 9) following the death of his father, King John (previous page). Notice in the second column, tenth line from the bottom, the script concerns "Willi comits Penbroke-magni" and goes on to record that William earl of Pembroke has become the Regent of England for the young king. (I don't read Old Latin - but I think that is the sense of the text.)
So with the authority of Sir Bernard Burke, we can be confident that the above image is similar to that borne by Sir Walter Giffard.
I must apologize for having earlier posted the image for Walter Giffard prematurely, which I have discovered with more research was for a cadet branch of the same Giffard family.