What is oscilloscope trigger "sensitivity"?
I too was wanting to know what trigger sensitivity was, and how it related to the trigger level. I found this article which explains it.
http://www.rohde-schwarz-scopes.com/_pdf/Benefits_of_RTO_digital_trigger_system-White%20Paper.pdf
Basically the trigger sensitivity sets the hysteresis level. In a complex waveform a trigger level may be crossed several times within a cycle of the fundamental frequency, creating multiple triggers within each cycle. Applying a hysteresis ensures that only one trigger occurs for each cycle of the fundamental frequency.