It looks more like the damage was done from the inside, but the glass was shattered with enough force that pieces fell inside.

As it is, picking up a shard shows her the moment the window was broken. Battler, having been in this room for who knows how long, can't find a solution to this erroneous puzzle. Not on his own. But he tries anyway. He takes a chair and throws it at the window, he even goes as far as to shove his hand between the broken pieces of glass, desperately desperately trying to get the windows open.

And then something grabs his hand. Another hand. It's cold and it feels wrong and the laughter is ringing out, the witch is thoroughly amused by his attempts. He tries to pull his hand back but the grip's too strong. And then. Around his left hand's ring finger... the feeling of a mouth taking it in and teeth... biting down. It's painful. It hurts. It hurts--he can't pull it free and then the teeth bite through--

Anyway, fortunately, your fingers are fine. It's fine.