"This book is interesting."
Neither of them have a qaghwI'. And there is actually a third meaning of Daj ("to test something inconclusively"). Context is very helpful in distinguishing, though you can also tell when it means "his/her/its" because it gets attached to the end of the noun it is referring to and the verbs will have a space separating them from any nouns.
nger Daj Daj paqDaj. "Her book inconclusively tests the interesting theory."