Slender Reed Meaning

(idiomatic) A person, fact, or resource on which one can rely only to a limited extent.

Example: 1888, G. A. Henty, In The Reign Of Terror, ch. 12:
  "It was perfectly natural for you to think that a lad of eighteen was a slender reed to lean on in the time of trouble and danger."
1908, E. Phillips Oppenheim, The Great Secret, ch. 35:
  "It is a slender reed," Gilbert said, "for so mighty an issue to rest upon."
2009 Sep. 28, Jeremy Warner, "Governments can survive recessions, but not in this case," Telegraph (UK) (retrieved 17 Aug 2015):
  Yet these precedents offer no more than a slender reed for Gordon Brown, almost hopelessly down in the polls, to cling to.
2013 Sep. 23, Lizette Alvarez, "Rubio Withdraws Support for Gay Black Judge’s Nomination to the Federal Bench," New York Times (retrieved 17 Aug 2015):
  The nomination of a gay black Miami judge to the federal bench will not move forward after Senator Marco Rubio announced he was withdrawing his support over concerns about the judge’s actions in two criminal cases. . . . “That is a slender reed for Senator Rubio to hang this on,” said Representative Alcee Hastings, Democrat of Florida, referring to the two court cases.