Good sculpting! But I am not sure about the heraldry, I never saw that for a member of the Valence family. May I ask for your source? Would be very interesting!
The knight on your source does have a very unusual pose for a picture on a effigy, I think it is from a seal (which would be a very typical pose on a seal).
I made a fast survey through my heraldry literature and my coat-of-arms rolls, but I could not track down the heraldry shown. The shield shows two "annulets" and the coat the "fleur de lys". The signs on the coat must not necessarely be part of the coat of arms, but I looked for both: Only annulets and annulets plus fleur de lys.
Got him! It's Guillaume Balnis, died 1289, Florence, Italy.
I've gone through Hewitts book (available as pdf on the net). He wrote on page xvi:
"58: From a marble bas-relief in a cloister of the Annunziata Convent at Florence, 1289. After a drawing in the Kerrich Collection, Add. MSS., No. 6,728. The knight, Gulielmus Balnis, among several singularities of equipment, presents us with a very unusual pattern of leg-armour : the whole suit will be duly examined at a future page. The composition conveys no very exalted idea of Italian art in 1289 ; and, in the drapery, the sculptor might well take a lesson from the humble chess-piece carver of the days of Magna Charta, whose handiwork was the subject of our last notice . . 244"
This could be crossed checked with the Osprey Elite No 19, "The Crusades", Figure K3. Additionally he adds to the relief in the Annunziata Convent a painting in the "Dante Hall, town museum, San Gimignano".
Congratulations, you have done a good representation of William (Guilemo, Gulielmus, Guillaume) Balnis, italian knight, 2nd half of the 13.cent,