Pfennig, penny, penning

Exploring Cybalist I have now reached December 2003 and a discussion
about the origin of Germanic 'Pfennig, penny, penning'.
A lot of suggestions for its etymology were proposed:
poena, panis, pannus…
I was surprised not to find 'pendere': weigh up (for paying).
Would it be incredible that a barbarian from the deep forest put a
suffix from his vernacular, -ing, -ig, to the oftheard order of the
caupo: "pende!"
The plural used for penny in English, pence, I myself have always –
without reflecting – associated with Latin pensum, Spanish peso.

Lars