On the body armor shuriken clothes it says that there is a 10% chance to fire a ring of projectiles when you hit an enemy with a single target skill. Would runes/skill tree nodes that say "Reduce the interval of buff by x%" increase the percent chance of the armor skill to proc?
I‘m afraid not, because according to the description of those runes/perks they only work on buff, and the skill of shutiken clothes don't add buff to character, so they certainly can't benefit from the interval perks/rune.