Jungler Upgrades Lack Clarity

I know Riot loves Clarity. They remind us constantly. Which is why I find it odd that the machete upgrades for smiting champions to either A) Deal X amount of true damage and apply a slow or B) Reduce incoming damage from target champion and deal Y true damage per attack. X and Y are unknown factors I would love to know. I think that Jungle Zed with a Challenge machete is a fun idea, but I don't know how effective it is. Update this please riot.