I do not think the coat of arms is English but could be wrong. You could check if your libary has the reference book that illustrates these - but not all do.
Or search on the web under heraldry and you will be able to find names for each element and names for how each is used on the arms. Armed with that you could then try googling for a match or write to the relevant college of arms. Try UK first, then Germany, France and Italy. If you are lucky it will not be a generic family arms but the variant for a particular member of the family and that will give you a very good idea of the date.
Once you have family and date its value can be multiplied several times.