I am not an "expert" on Ardvorlich, however, I do have a photocopy of one of the 9 remaining copies of "The Heraldry of the Stewarts, with notes on all the males of the family, descriptions of the Arms, plates and pedigrees" a rare book authored by G. Harvey Johnston. It lists:
"Murdoch Stewart, Duke of Albany and Earl of Fife, also Earl of Menteth (S.) in the right of his mother Margaret, Countess of Menteth. The Duke left the following sons: ---
(a) Robert of Fife, died without issue 1421.
(b) Walter of Fife, executed 1425
(c) Alexander, executed 1425
(d) James had a natural son, James Beg, whose descendants are the Stuarts of Annat, Stewarts of Ardvorlich, Baldoran, Ballachallan, Craigtoun, Duchlash, Gartnafuaroe, Glassingall, Glenbucky, Hyndfield, Ledcreich.
Arms of Stuart of Annat, same as Ardvorlich, but with black mullet in the centre of the quarters (Burke).
Arrms of Ardvorlich, recorded 1802. --- 1 and 4. Scotland. 2. Gold, a fess chequy blue and silver, in chief a red mullet. 3. Silver an engrailed saltire between four roses red. All within an engrailed bordure compony, blue and silver. Crest: A right hand and arm couped at the elbow brandishing aloft a broad-sword, all proper.
Motto: "Deo juvante vinco" (Lyon Register)"
The arms are "quartered" -- having 4 sections. To be "proper" is to be of natural colors or tincture.
I hope this is of help to you.
Chair, Genealogical Committee
Clan Stewart Society in Americahttp://www.clansstewart.org