Door knocker From University, Very old

This item is originally from the Groningen university, founded 1640.
Sorry if in wrong category.
The knocker itsself is 7.5cm long and in 5 width and the whole thing is 130 grams.
In Latin: Academia Groningana. The text on the book says: 'Verbum Domini lucerna pedibus nostris' It is worn of but could match it with the one on the building.
It has the shield of Groningen on it. I assume it is brass, The part that is mounted to the door looks like copper On pic 4 you see the backside.

Has anyone an idea how old it might be?

http://en.wikipedia.org/wiki/University_of_Groningen