I am not a fan of the power weapon changes.
hrmm, I both like it and don't.
It returns the primacy of 2+ armor, which is good, in some ways. Artificer and Termie armor was feeling a bit pointless on most ICs, who usually had a invo save, and were going to be targeted by a power sword anyway.
I worry that this exacerbates the supremacy of TH/SS termies, though. However, it does reinforce the primacy of dakka as how to kill termies, so....
Very few things have AP2 but don't strike at I1 besides MCs. Warscythes (but they're i2, so what's the difference) and the demi-flaives of incubi sergeants, which drazar also has, so he's super dangerous.
A few interesting things about the big heavyweight ICs....Mephiston versus Draigo is basically a slap fest, until presumably Meph misses a save and gets his soul sucked. But there's a half decent chance (after 3 or 4 turns) meph wins. On the other hand, Ghazgull can pretty clearly beat Draigo.
None of the DE archons special crazy weapons are AP2. You're only option for him is to give him a power weapon, model it as an axe, and I see basically no one doing that. Also, elves with axes looks silly.
Generally speaking, IC will try to get 2+ armor where they can, and then mostly fail to hurt each other in CC. You might see some SM captains with power fists now.
Oh! There is point to having power weapon and rending now.
It has what I see as some pretty massively unintended consequences, too. DCAs I'm going to model with both an axe and a sword. Then they can go at I6 or 1, as they wish, and still get the +1 attack. This also aids with "sniping" various models. If only one model is going at i6, the model it's in Btb with (if there's only one) has to take the wound. I don't see any reason not have my i3 crusaders modeled with axes.