Mainly because a warrior may not have more than 2 HTH weapons, 2 ranged weapons, and free dagger. The combination in this case would be Fighting Claws, Free Dagger, and Fist.
In the past I have also used a combination of 2-handed weapon, sword, free dagger.
I have had discussions with some on SG Forum (Before Shut Down), that a 4 armed, or more, mutant still canít wield more than 2 HtH weapons at a time. Therefore, he couldnít even use his free dagger at the same time as 2 swords. Also, since he can use weapons, he could not hit with his fists unless he only wants to hit once per turn. And when I asked about the extra attack for each new arm provides, I was told, he would use his weapon wielding hands instead. And the other arm could just hold shields, bucklers, or just wave. I thought it rather silly to have 4 arms, 3 HtH weapons carried, but could only use 2. Like Tail Fighting for Skaven, using Fighting Claws and Free Dagger in the tail. Again, some said this only works if the Skaven is skilled in Art of Silent Death, where he could fight unarmed and wield a dagger in the tail. Again, I thought it was rather silly.