cái liềm sounds like "ký liềm" here
In everyday speech the article "cái" is shortened to something like "cấ..." as in a short "cớ" or as you stated, a short "kí" sound.
Good to know, thank you ^^
How would you then say "How do you know that ancient sickle?" From what we have been taught, that would be the usual translation.
làm sao bạn biết cái liềm cổ đó?
the demonstrative determiner should be at the very end of a noun group. a short reminder:
quantifier + classifier + head noun + attribute + demonstrative determiner + possessive determiner