Humility's design with his disappearing stripe-things make him seem smaller than he is. His corrupt form does the exact opposite of this, seeing as the stripes now flow outwards to make him seem bigger.
Temperance's design being extremely minimalistic, even in comparison to the rest of the Virtue designs. Considering he represents moderation and all that, why would he even have a more detailed form than what's necessary?
When the second Chastity gets angry, his eyes turn completely purple. Now compare this to the first Chastity, who was pretty much a perpetual grouch and has monochromatic purple eyes.
The first Peace just fading away. One could say that she died peacefully.
Temperance being a surrogate father to the second iteration of Peace, Irene. What is justice supposed to maintain? Peace.
The Final Battle between Heaven and Hell brings up a lot of this.
Imagine being a host or at the very least known one of the Virtues or Sins as the final battle comes up, knowing full well that the world is going to end because of them and that that's only the collateral damage.
On a similar note, the Holy Hell/Seraph modes is freaking terrifying in concept. They essentially give up whatever shred of humanity they have to gain these powerful forms, and using Humility as an example it takes a ton of control to keep said humanity in this state. Whatever amicableness they had between the two sides is thrown out of the window as Sins become more animalistic, while Virtues become more one-track minded to destroy their opposition. Oh, and it's implied that they're somewhat aware of what's happening in this form, so they might be fully concious of the fact that they're killing their loved ones directly or indirectly.
Then there's the other side of the scope humanity kills themselves long before the Final Battle starts. Considering that Personifications in general feed off of their respective aspects they represent off of humans, then essentially they'll die slowly until the final human dies.