Regarding "Bleeding doesn't work in the new Arena"
It does work. The bleed stack count is just hidden. I literally just tried this myself and I can see the difference in damage numbers. You can also tell that the bleed stacks are working because Kill Thrust only does the "deep stab" animation and gives invincibility when you reach 10 stacks. I also tried using Kill Thrust without using any bleeding skills first and it doesn't do the special animation for invulnerability. I don't know if other debuffs are also hidden or just don't work (Frost Mage), but at least for bleed I'm pretty sure it's still working.