This paper reexamines the correspondence of Classical Armenian -rk- with Proto-Indo-European *du̯ and attempts to explain the change in a phonologically plausible way without recourse to illicit clusters or ad hoc rules not otherwise operational in the language. Instead, the change of *du̯ to -rk- is analyzed in Optimality framework as an instantiation of the Armenian sonority-based metathesis. Instead of the expected segment metathesis, however, I argue that this cluster underwent metathesis only of the feature [±continuant]. The need for feature metathesis rather than segment metathesis for this sequence was motivated by a TETU effect (The Emergence of The Unmarked) due to the markedness of the segment [w] in Classical Armenian. The markedness of [w] in Classical Armenian is supported by the later glide fortition seen in forms such as gini “wine”, from PIE *u̯oinii̯o-.