Some of the armour set bonuses are incredibly pathetic. Was just looking at my champ's set and the 3 piece bonus for Delaulagos is to reduce the cooldown of seeking blade by 2 seconds. Normal cooldown is 2 minutes so this is basically a 2% reduction which you can just forget as being any use whatsoever.
If it was a 25% or 50% reduction then that would be well worth having but frankly I find it insulting that whoever spec'd this thought it would be useful. I've noted other instances of similarly useless reductions and wonder what these people were thinking of.
Every use of brutal strikes reduces cooldown of seeking blade by 2 seconds. Ask yourself how many times do you spam brutal strikes in 2 minutes, then multiply that answer by 2 seconds and that's how much the CD is reduced by that bonus.