a) Awakened Animal Companion regen from Blood Lust is lost upon rest, even though Awaken persists
b) Vamp Regen remains even after Blood Thirst expires of duration (not sure if this one happened before the feat, didn't spot before)
Steps to reproduce the Bug:
Be ranger with 15+ levels, have Blood Lust feat.
a) Summon Animal Companion, cast Awaken, then rest.
b) Cast Blade Thirst, wait for it to expire. Hurt yourself, then try to attack any monster.
Expected Result:
a) The beast keeps regenning if hurt after the rest, as Awaken never dropped
b) Vamp Regen is lost once the spell expires
Actual Result:
a) Beast doesn't regen if hurt
b) Vamp Regen (both enhancement based and con based) keeps happening even if it expired. Examining weapon shows that the OnHit quality still remains while enhancement is lost
Screenshot(s)
Don't have screen for A; as for B:

16 Con, 15 levels, so 5 regen (3CON + 2Enhancement)
Weapon only has +2 Pos Perm Essence and +1 Acid Temp Essence, otherwise basic bronze