Dear Mr. McElrea,
I don't think that it's possible to discern anything from the image you've reproduced. It appears to be a nineteenth-century copy or version of some earlier original. It's entirely possible that it's removed by more than one generation from that original. A quick search on Google Images reveals
this version of your image; note the caption, which describes it as being "From an engraving by William Holl". Note also how the sleeves, which ought to be mail, resemble sweater sleeves; and the detailing at the shoulders and around the armpits, which might be meant to represent pauldrons, is, to put it mildly, confused.
The original portrait may be
this image. Regrettably, this view is cropped; I'm afraid that I couldn't find a full version. At least in this, points are visible along the shoulder-line, suggesting that the armor may be an embossed plate harness or corselet.
I hope that this proves helpful.
Best,
Mark Millman