Lord Erskine's arms were:-  Quarterly, first and fourth, Argent a pale Sable between two lions rampant Azure armed and langued Gules (for Erskine) second, Argent a saltire Sable between a label of three points in chief and a mullet in base Gules (for Maxwell) and third, Argent three urcheons Sable (for Herries). The Maxwells of Rerrick did not have registered arms and one supposes that the Maxwell quarter was 'invented' by adding the mullet (star) to the Maxwell, Lord Herries arms  to give an indiction of the apparent descent of the Rerrick cadets from John Maxwell, Lord Herries.  John Maxwell, Lord herries arms are the same as the above maxwell and herries quartering but with Maxwell in fist and fourth and herries in second and third and of course no mullet! In Lord Erskins arms there is an inescutcheon with the red hand of ulster but this is to indicate that he is a baronet of of the United Kingdom. There is also a collar and badge around the arms of a Knight Grand Cross of the most Excellent Order of the British Empire. The supporters are two Griffins rampant parted per fess Gules and Sable powdered with bezants and armed Argent.  I have no idea how the crest has been actually blazoned but possibly something along the lines of:-  an arm issuant vested Sable and Azure with a maunch cuff also Sable and Azure, the hand grasping a pole axe in bend Proper.