Wd/w is still very much a viable tank combo. Unlike the knight, they are more of an agro tank than a mitigation one, requiring higher dps to build and maintain agro. They do also have the option to wear plate if you so chose. The real reason there aren't more of them (anymore) is the elites - k/w has AD which gives a short party buff to damage while the wd/w has feral leader which is only a self buff. None of the k/x combos does amazing dps so if you have a low dps party a wd/w might be more beneficial. It all really depends on the group you run with and what their capabilities are.
Titaia (100/100/55 M/P/K), Safia (100/100/75/60 K/P/W/S) - Badkitty
Vivecka (100/100/60 Wd/W/S), Tuulikki (100/100/84 Wd/W/S) - Unity
Vanora (100/70/70 D/Wd/S), Morz (100/100/83 R/S/Wd) - Aurora
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