I would use a variable, and a #IF statement in the trigger value to detect if it should cast the spell or not...
pattern: You feel less armored
#CW Cyan
#IF (@spellson) {c armor}
This would only cast the spell if the variable spellson was not 0...
use #var spellson 1
to turn it on, and #var spellson 0
to turn it off. (this could be put into aliases, or my personal favorite, toggle buttons...)