Ordered from most useful:
Teddy Bear>Tirfing>Khalitz
I think u may have made a mistake here...In order of most useful It'd be:
Tirfing > Teddy Bear > Khalitz
Clearly tirfing is going to be the most useful shield do to a large amount of medium size enemies in this game and the fact that players are medium. Now narrowed down just to include niff, I believe tirfing to be the best as it reduces dullahans
and disguises. While teddy bear reduces more from dullahans and khalitz more from disguises, tirfing gives 25% over both of the two most damaging monsters in niff.
And I'm not biased towards tirfing for ne particular reason. I used khalitz for over a year be4 I finally gave in and switched to tirfiing after noticing a drastic improvement in dmg received and overall survival.