Looks like rifle
Markings on back
Your picture of the hallmark and sponsor’s mark is too blurred to make out the details. I think that the sponsor’s mark is WAH but I can’t be sure. From the fact that there are 3 parts to the hallmark I deduce that it is probably 20th century or later which is supported by the style of the brooch. There are no comprehensive references to modern Irish sponsors’ marks and WAH is certainly not known to me. To tie down the date I suggest you refer to my table of Dublin date marks.