زَيْدٌ أَسَدٌ
Zayd is a lion.
With no kāf, the predication directly casts Zayd as a lion. With no “in courage,” the utterance does not explicitly restrict the likeness to one feature. Their combination can yield the strongest impression of rhetorical identification.
By contrast, “Zayd is like a lion in courage” has both forms of restriction: the particle preserves overt comparison, and the stated respect singles out one trait. It is more explicit, but less intense as an overstatement of identification.