Well what I do know is how it used to work: suppose a mob would do 30 dmg, stb+cut and you would have 40 cut protection and 0 stb, that would lead to 1.0 hits from the mob, cut protection absorbing all dmg through protecting the whole damage. First time mentioned by Pham, when he started an epic thread regarding kreltin's acid damage, where people in Angel were providing proofs with 1.0 dmg. i understand this mechanic was changed, so distribution would be hard at each hit. Either that, either probability, so x% hits would be pure stab in my example, y% would be pure cut and z% would be combinations.
I do have same problem with berycled, but quite complicated to test.
However, why would you use t-bird with 6b? That is a generous overprotection on 50 dmg from gen1?
If your armor is UL, maybe you had a blonde moment and one of your pieces is 5% condition or unequipped? These would be obvious scenarios. If is (L) and you wear all pieces, that leaves room for a single explanation, that this mob (or more of them) has hits of pure dmg, in this case pure stab (as per General's description of Rextelum), but then again it could be 46.4 only if you wear UL armor and that particular piece has a tt condition of about 30% (in order to affect Tbird's 8 stab vs. evis 50 dmg).
Oor they been added a new dmg type and had a 46.4 hit on that dmg, but considering Aio's test, that is quite out of the way.