broken reed

From broken + reed (with reference to quotation 1611, below).

broken reed (plural broken reeds)

1. Something or someone very fragile or unreliable.
   • 1611, The Holy Bible, […] (King James Version), London: […] Robert Barker, […], →OCLC, Isaiah 36:6:

     Lo, thou trustest in the staff of this broken reed, on Egypt; whereon if a man lean, it will go into his hand, and pierce it: so is Pharaoh king of Egypt to all that trust in him.

   • 2002, Colin Jones, The Great Nation, Penguin, published 2003, page 543:

     Many of the big estates survived. Nor was the peasantry a broken reed in terms of demand for manufactured products.

   • 2011 July 5, Simon Jenkins, The Guardian:

     A law on privacy would be cumbersome and hard to police, but as the Press Complaints Commission is a broken reed in this matter, each scandal makes it harder to stave off calls for legislation.