LostSoul
Adventurer
Light can't target creatures.
Yeah, but it's cool, so I'd say yes and allow it! If you don't think it's cool, then tell the player he's lame and should just go home.

The "Blinding Light" power I wrote is just something for useful adjudication of how I would handle that cantrip in my own game. Other people might let it do more, others less, others not let it work at all; hell, I might rule that in a certain circumstance (fighting in pitch-black) it might do damage as well!
It'd be wise to be careful with this. It'll start with using a cantrip to blind an enemy. Next thing you know, you're rolling perception checks for the Dragon every round because the Ranger Twin-Striked his eyes out in the surprise round and the Warlock is wanting to know if he can Hurl only the head through Hell.
It's nice when it's cool and original, but I'd avoid doing it if it can be used constantly and raises the power of anything significantly.
But, maybe I'm just a jerk.
Agreed; the key thing is that you don't want to allow something that's too powerful - either an attack or damage - with your ruling. Simply making Blinding Light cost a standard action probably does this; it's good in some circumstances, but not as good as a Thunderwave or Cloud of Daggers in others.
If the Ranger wants to cut out the Dragon's eyes so that he can't see anything, tell him it's too much; maybe he can give it the same -2 to attacks (or daze or blind it at higher levels), but he won't deal damage as well. The Warlock can try to hurl only the guy's head through hell, but since that is basically killing him, he'll have to reduce him to 0 hp first!
What I want to eventually do is go through the powers, make a list of general effects that you can do at each level with a standard action.