Sentence 1： I was told my work was unsatisfactory, at which point I submitted my resignation.
Sentence 2：Sometimes you may feel too frail to cope with things, in which case do them as soon as it is convenient.
I am confused with "which" in the above two sentences. Does it serve relative determiner, rather than relative pronoun? Does "which point" in the first sentence stand for "I was told my work was unsatisfactory"?Does "which case" in the second sentence stand for "sometimes you may feel too frail to cope with things"?
Thank you in advance!