Hello guys!
I've noticed that monsters' weapons lacks of a size descriptor (in OQ as well as in RQ SRD). never been a problem until one of the characters tried to parry a centaur kick with a small shield.
Even if the shield was a buckler, I've decided that it would absorb the whole damage (because small shield=medium size)... but I'm not sure about the choice. And now I'm losing my mind thinking about parrying dragon's tail whips and other monsters' big natural weapons.

Is there a way to determine (loosely) the size of monsters' natural weapons?

Taking the dragon chart for my example, I've opted to match the monsters' weapons damages with the closest crafted weapon's damages. The result is:
bite 1D10 (like a lance, Heavy)
claw 1D8 (like a lot of one handed weapons, Medium)
tail 1D20 (more powerful that any crafted weapon... Huge)

What do you think about it?