I might make you happy with this and change what you expect
When Inferno came out that insane last boss required the best knight or just good ch/k to do it, it was impossible to survive other way. Giants is way different and is not bound to new meta-op tank classes like inferno was. Ive seen tanking giants all kinds of tanks, k/w, k/s, k/p, ch/k, ch/r, ch/w, ch/p.... even w/m when main tank dies can hold most of the bosses, all this with a normal tank sta/hp gear. Yes, wd/w is in that list, is possible.
Ones are more efficient or atleast, easier and more enjoyable to play than others, but all can do the job in terms of survability. The main problem lately is the aggro. Most of endgame dps changed to champ because is the new meta class in giants, so more than the question being able to tank (like always), now you need to ask if you are able to hold their crazy aggro. I think wd/w could, specially with the new plate refined set.
Summing up, play whatever you want, at this point of the game is possible to do it with multiple classes, specially tanking.
Cheers, Madoxx.