Mutant Maneater Fireball + Shield?

So on my giant, if I get hit with the Maneater's fireball while I have a Vales Shield equipped, I seem to take very little damage, unless I am in the middle of a casting animation. Does this work for other races/shields too, or is it because of the ridiculousness of said shield? Or perhaps a bug?

Vales Shield gives the largest bonus due to it being the only large shield. Fire Shield also reduces damage, so it may have stacked on top of Vales Shield.

Sigh, this keeps spreading like the plague...

Vales Shield + Defense Skill = All damage outside of duels lowered to 1. Yes all damage, including a 10k from Red Dragon.

We don't know why this works though. Either DevCAT tweaked the Defense skill in favor for Large Shields or a really weird bug. IIRC someone said that its like this in KR, too.

It doesn't work with Medium or Small Shields, but I have no idea if them + Defense significantly reduces damage.

Apologies if I was spreading bad information or an exploit. I was more curious as to why it worked like that. I can definitely do some testing, though.

Quick and dirty test: ~1.3k with human/plain kite shield/Defense skill not used, ~500 with human/plain kite shield/r7 Defense skill used. So non-large shields have some kind of influence, just probably not enough to actually matter in comparison.