expression, adverb
clumsily; with clumsy hands
Describes doing something in a fumbling, unsteady, or suspiciously awkward manner, often implying lack of skill or nervousness.
彼は怪しい手つきで包丁を使っていた。
He was using the kitchen knife with clumsy hands.
怪しい手つきで書類をめくる。
I flip through the documents clumsily.
不器用 is a general adjective/noun for clumsiness or lack of dexterity, while 怪しい手つきで specifically describes the manner of hand movements as awkward or suspicious-looking.
A set phrase combining 怪しい (suspicious, dubious) with 手つき (hand movements) and the particle で, literally 'with suspicious hand movements', used adverbially to mean 'clumsily'.