Just as the name says, I'd prefer to have edges of the screen painted with damage type received (several separate layers if receiving several types of damage.
Blinking knight is hard to notice in a crowd unless I'm looking at the knight. Thus I miss the point where I get damaged (thanks to lag I can get damaged by melee monster across the map).
Also, blinking knight is very very misleading. In most arcade games when you receive damage and start blinking it means you're invincible for a second or so. In Spiral Knights it means you've been damaged and you can still take damage.
Basically, I want better damage indicator. In worst case scenario add a sound when knight gets damaged. "Ouch" will do.
A sound IS played when you get damaged(but the "ouch" could be more comical)
Also, are you sure that you can get damage when blinkin? If that's true, then every time i fall into a spike trap i'd be dead because of constant damage.