@mais, that is a great little billon coin you have there. It looks to me like it is a Dinheiro issued by Alfonso II of Portugal somewhere in the mid-13th Century AD. Here is a numista link to one such example for comparison:
I may be trying too hard to interpret the messed up parts of the legend but I seem to see a "D" on the top of the first pic. The legend would then readl "D REX PORT" meaning it would be from Dinis I (12t9-1325). But as I said, the legend is a bit messed up so I might be imagining things. But it does seem more like a D than an A.