It is dated 1223/12, I think. In my innocence, I would take it for KM 150.2. KM doesn't list regnal year 12, but there are 10 and 20 para regnal year 12 that are the same type as regnal year 13, so why not a 40 para regnal year 12 that is the same type as regnal year 13?

Your coin is a bit lightish for a 40 (it should have been 14 gram), but KM notes: "There is considerable weight variation within each denomination, in some cases up to 20% higher or lower than the theoretical norm". Yours is 30% lighter. However, a 20 para should be 7 grams and that would make it almost 40% too heavy, so I still prefer to see it as a 40 para coin. See

Numista for a picture of KM 150.1.

Peter