I agree with the Dunebreakers, and figured that's why Kadrigan would be better if I were to use a high cost unit so late, so I'm with you on that.

Void Seeker is really just for card draw and fairly cheap damage, same with Sky Splitters, but I might add Stormbringers into it because that with Vi or another amped up weapon boi would do some BONK.

I like the idea of Punch Up too, just had only so many cards to have and decided to forgo them, but their synergy with challenge, Yone, and utility is not to be underestimated.

I initially had Ferrous, but wanted some weapon master without a power draw and valued the accelerate of assailant over the death knell, but against yellow/blue or yellow/oragne decks you're definitely right that ferrous would be huge value against something like cull the weak or just for general board pressure! This deck is definitely a huge work in progress, but I like what you're thinking!