Of course, the term "Eibar" could apply to any of the makes under discussion; all the companies were in the Basque region around that city.
As to the "sealed pattern", yes that means that there was a gun "sealed" (it literally had a wax seal put on it) and it became the standard for production guns. The maker(s) could change, but the product had to be as identical as possible to the sealed pattern. Given the state of Spanish arms production at that period, I would expect that only the maker of the sealed pattern revolver would be able to produce guns close enough to meet requirements (and maybe not then).
So, Ron, assuming you mean Orbea, not Obera, you have thrown yet another Spanish company, Rexach & Urgoite, into the discussion. I wonder how many companies made, or tried to make, revolvers in .455 for the British and how many actually were accepted.
Jim