An appendix in the 2nd edition of Spanish Best by Weiland lists an Parkemi Armeria in Eibar, and a Pedro Arosa Aguirre in Elgoibar, in addition to the top line Pedro Arrizabalaga in Eibar. There was a web site devoted to Spanish gun makers, but my link seems to no longer work. Maybe someone else has a new link, they might show various symbols. My guess would be that it's not an Arrizabalaga, perhaps one of the first two name suggestions.