Putting Holes in coins is not always for decoration! The practice of holing counterfeit and European copy Edward I,II,& III coins was practised, mainly because the general populace were pretty ignorant. I presume it was officials that pierced them, but left them in circulation because of the shortage of coins, probably at a lesser value!
BTW. The coin shown is William 1337-91 of Namur, a Crockard