The governor shall have power to remit fines and penalties in such cases and under such regulations as may be prescribed by law; to commute capital punishment and, except where the prosecution has been carried on by the House of Delegates to grant reprieves and pardons after conviction; but he shall communicate to the Legislature at each session the particulars of every case of fine or penalty remitted, or punishment commuted and of reprieve or pardon granted, with his reasons therefore.