If James Davies of Moor Court had included a "name and arms" clause in his will leaving his arms to his great nephew James Banks then the descendants of James (Banks) Davies would undoubtedly be entitled to those arms according to the law of arms. If he only left a name clause the arms would not have been inherited by James (Banks) Davies.

Without a specific destination mentioned in a will then the arms would be subject to the basic laws of arms and could only he inherited by a son of James Davies of Moor Court. With a specific destination, through a name and arms clause, the arms could be gifted, through the will, to practically anyone the testator wished subject to the success of the Royal Licence (or act of parliament).

I do not think that a simple "name clause" would be sufficient however if you feel that (or another) might benefit (armorially) from the will then it would be worth contacting the College of Arms to put the case before a herald. One never knows - after all, they have the "Ways & Means Act" at their disposal.

Regards,
Martin