Hi Chregu,
I love it! These are a favourite of mine, they used to turn up on ebay quite regularly, but not so often now.
It's Spanish, as you rightly say. Probobly made in the knife makng centre of Albacete. I have a similar one, as do others here, so hopeully they will join in to show you other examples.
Yours is known as a 'Punal type A'.
I would estimate its age as mid 19thC, but it could be as early as late 18th.
A desirable item for sure.
Here's a thread dealing with these and associated Spanish daggers/knives.
http://www.vikingsword.com/vb/showth...8&page=1&pp=30
Here is a great resource page for examples of the entire 'range' (including translation from French):
Spanish Daggers
The national knife of the canary Islands seems closely related, here are mine with some of them: