I'm not sure why you would go the 1/2 Angel / Spanish route? It says England to me. The standing figure is clearly St George standing astride the recently slain dragon which would narrow the choice to GB or Russia I reckon. As his chest plate shows the English flag I'd discount Russia.
You're right with the period though. From James 1st onwards merchant weights were required to carry the date.
There's not a lot of information on the subject but if you have the time and patience try searching the
finds.org database and see if you can get a match.
For values, it's going to be tricky as they're often sold as sets but you might find this useful to get a ballpark figure -
http://www.abccoinsandtokens.com/Coin%20Weights.html
Good luck, hope this helps some and please keep us posted if you find anything.
Non illegitimis carborundum est. Excellent advice for all coins.
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