The unfortunate thing about these mint darkened farthings esp the war ones,is they can be badly struck and the part of the coin that is usualy badly struck is britannias head this often leaves many collectors with the wrong impresion as regards grade .
A coin can be unc or near to and end up looking less than EF grade with a badly struck head .
TBH these coins are a bit of a nightmare to grade anyway .
The best thing you (the collector) can do is just get a coin that pleases you and stick with it , in the end very little else matters.
If you like a coin you can bet your bottom dollar another person will as well, so although common it should have a resale value .