wiseacre means "one who feigns knowledge or cleverness; one who is wisecracking; an insolent upstart." If you made a joke somebody might say "oh, a real wiseacre, eh?"

seeing Weizsäcker's name I was struck by the similarity so I thought I'd look it up, and turns out the two words have the same etymology: soothsayer, wise man

wiktionary From Middle Dutch wijssegger (“soothsayer”), from Old High German wīzzago, wīzago (“wise man, prophet, soothsayer”), from Proto-West Germanic *wītagō (“wise one; prophet”). Cognate with Old English wītga (“wise man, prophet”). See also German Weissager (“soothsayer, seer”).

https://en.wiktionary.org/wiki/wiseacre