[quote=@Feisty-Pants]
<Snipped quote by Override>

It's not just hardness that you should be worried about. It's raw, hardened light, which means it's compressed to a degree far greater than a laser or something relatively similar, putting it under an immense degree of pressure.

What happens when something under massive pressure is abruptly fractured?

Explosions. White, blinding, fiery explosions. Probably equivalent to a mortar or a hand grenade. 

That is if she chooses to. Which is only rare, since it would cause extensive collateral damage. She's self limiting by that degree. 
[/quote]

Actually light doesn't hold that much pressure. Being massless particles and all. Plus light is not bound to the Exclusion principle so you can technically compress as much as you want. It'd only glow brighter. :P