Okay, where to start. The first thing to do is to go to the sources and find the descriptions of the banner. There are two - One quote is from William of Malmesbury's "Gesta Regum Anglorum", and is
as follows.
"Vexillum illud post uictoriam papae misit Willelmus, quod erat in
hominis pugnantis figura, auro et lapidibus arte sumptuosa intextum"
As best I can make it, this is
"That standard, which after his victory,
was sent by William to the Pope, which bore the figure of a "fighting
man" , richly embroidered with gold and gems."
Now, my text translates it not as "fighting man", but as "warrior". I
believe the Latin present participle "pugnantis" can be taken two ways.
One, as a man engaged in fighting; the other, a man whose occupation is
fighting, much like even today we refer to soldiers as "fighting men".
William of Malmesbury was writing about fifty years after Hastings. He was born about the time of the events he describes.
William of Poitiers, who had much better access to the facts - he was a
chaplain in Willaim's own court, and therefore may even have seen the
banner - described it as;
"Memorabile quoque vexillum Heraldi, hominis armati imaginem intextam
habens
ex auro purissimo..."
[also [sent to Pope Alexander] Harold's famous banner in which the image
of
an armed warrior was woven in pure gold.]
In fact, the translation would probably be better "an armed man" or "a
man of arms"
I believe the idea that the banner was covered in gems to be a later addition. William of Malmesbury never got the chance to see the banner - it had been sent to Rome - and would have been relying on other people's garbled memories fifty years on, or just copying (not necessarily accurately) from other accounts, such as William of Poitiers'.
I also believe that there's a good chance this was a standing figure of
a military saint. Taking into account the fairly specific description
by William of Poitiers, the equivocal (and later) description of William
of Malmesbury, and several examples I have seen myself, it seems to me that the banner was of a warrior, not of a person engaged in fighting.
There are contemporary pictures of this type showing military saints
like St Maurice, St George and St Theodore & St Demetrios (Byzantine). England had such military saints as St Edmund, and St Guthlac,
and there were the two St Olafs of Scandinavia, that come to mind
immediately (Harold WAS half Scandinavian).
I could put my hands on maybe half a dozen pictures from the right time
and roughly the right region, of military figures standing holding their
weapons - rather like the "Goliath" at
http://prodigi.bl.uk/illcat/ILLUMINBig. ... &IllID=467 or another at
http://www.angelfire.com/empire/egfroth ... ii_f30.jpg (Angelfire won't let you link directly, so you'll have to copy and paste the address) or
http://www.geocities.com/egfroth/ASFeastGuard.jpg (all Anglo-Saxon), and others from Francia - see
http://www.geocities.com/egfroth/StMaurice.jpg and
http://www.geocities.com/egfroth/MauriceMainz.jpg , Italy (
http://www.geocities.com/egfroth/AtlanticBible2.jpg ) and Spain, such as
http://www.geocities.com/egfroth/BeatusWarrior.jpg . And that doesn't take into account the Bayeux Tapestry, or the Byzantine Saints who
were VERY commonly portrayed thus. If Byzantium, Spain, and France
have examples of this type of thing, it seems to me likely that England
(which had a well-deserved reputation for fine embroidered work) would
have produced something similar for Harold's banner.
For a royal banner, woven or embroidered with gold, I would assume the fabric would be silk. The most expensive colour available would be bright red, as the dye (kirmiz) was very difficult to get hold of, and expensive in its own right. Not to say the Anglo-Saxons used the dye, but that red-dyed silk was imported (there was at least one find of kirmiz-dyed silk found in Jorvik).
Probably a rectangle with the saint on it, with several triangular tails - like the banners in the Bayeux Tapestry - like the one in the top panel at
http://www.angelfire.com/rnb/bayeux_tap ... 43_45.html , but a bit bigger, as it was more important.
The "fighting man" should be in the Anglo-Saxon artistic style, as shown in the examples above and others. You need someone with a good artistic eye to do this - duplicating a particular style isn't all that easy.
The banner should be in gold, and perhaps other colours, on a (red?) background, with a gold-embroiderd border in an Anglo-Saxon style - there are good examples of the correct styles at
http://www.uvm.edu/~hag/rhuddlan/images/ (keeping in mind that at the time this banner might have been a century or more old).
Fo examples of what the English were capable of around this period, see the top picture at
http://www.christusrex.org/www1/vaticano/S2-Sacro.html - a cope made in England, c. 1280-1300 (red silk twill embroidered with gold and silver-gilt threads), and if I can find it, a stole in Durham Cathedral dating to the 10th century which is nothing short of magnificent - aha! Here it is -
http://www.geocities.com/egfroth/Cuthbert2.jpg .
These are the ideas I've already worked out for my own planned banner, but that's really as far as I've got. Hope this helps. When you've got a concept worked out, send it to me and I'll let you know if I think it looks right.
Good luck with it.