Yeeees, but -through- him being capable of RPing a Blademaster very well, he managed to make -the actual character-, that is ICly, more than just a 'regular Blademaster' as well. He was an actual character, in every meaning of the word. Not just the concept that defines a Blademaster. In my eyes, it takes more than just the concept to make an orc. Krogon earned the reputation he did because of the way he RPed a Blademaster (as in, his own execution of it) as well as the actual RP he did beyond that mere concept alone. He actually initiated RP, created hooks for people to jump on, etc. Those aren't necessarily things any regular Blademaster would do per se.
And even if it wasn't for that, I don't really see why one wouldn't (ICly or OOCly) be able to praise a character just because their 'class' is considered OP by default. Demon hunters, death knights, dark rangers or even Warchiefs are considered hero classes or OP positions of power comparable to, for example, a Blademaster (at least going by what they represented in Warcraft III). But certainly not every character that RPs such a role can be considered neither OP or particularly impressive.