The direct examination of 14th Century armour is often a lot more difficult than the later 15th and 16th Century equivalients. Very little primary examples survive from the period in relative terms to the later two centuries. This often means that in attempting to understand the fashions, functions and fads of a specific era we have to turn to the examples left us in monumental effigies, brass rubbings and illustrations.
Care must be taken when using these resources to assist in our decisions surrounding our armour, as was described to me recently, 'I can draw a fairly detailed tank but you wouldn't want to make one from it'. This same caution must be used when examining these pieces of superb artwork. The stone mason, bronze caster and illustrators, while masters of their own crafts were in all likelihood, not, expert armourers. They may have seen it, may have even, in some rare cases, had it to work directly from. However their different mediums and briefs would all present a different set of criteria that might change the final piece from its original counterpart.
A marble effigy is designed to last for centuries were as the armour the man was wearing, no matter how nice had a function very different indeed, to protect its wearer from harm either at sport or war. So subtle differences are often missed to the requirements and skill of each craftsman.
Below are a series of links that can take you to some fantastic study, images and details on the monumental images through our period and beyond, but the warning must be to notbe a slave to their detail, but use them as guidelines in comparison to any existing material we are left.
http://effigiesandbrasses.com An incredible collection of images of brasses, effigies and illustrations of 14th century armour. The picture above is from their site.
Talbots Effigy Analysis a superb piece of work on comparisons from one decade to the next of over 1300 effigies throughout Europe.
A very image heavy effigy list in chronological order.