Just to name one example, Snowden disclosed the America's wiretapping of 35 foreign leaders: https://www.theguardian.com/world/2013/oct/24/nsa-surveillan...
As for "articulating an impact" that's both obvious, a big diplomatic incident between the US and the nations whose leaders it was targeting, and IRRELEVANT. Snowden was trusted with Top Secret information and it was his duty to protect it, whatever he thought the impact of leaking it would be notwithstanding.