Are there any other cases of German ver- in place of Latin sub-?

Not that I can think of at the moment. The prefix ver- is cognate with English for- and so started out as a kind of spatial verbal particle, like ueber- or unter; cf. English forbid, German verbietan. There is unternehmen (literally, 'to undertake') meaning 'to venture, wage'.

Ceci n'est pas un seing.