"Tanks," Multiple enemies, and combat vs. multiple, unique foes

You want “Fighting Multiple Opponents” starting on p459.

If you’re using foes as groups, it’s basically irrelevant what most of them are wielding (despite what the book says). You can have one guy with a sword as the primary opponent and two helpers giving +1D because one has B3 Axe (and an axe) and the other B3 Mace (with a mace). Sword guy acts like any single opponent, but with +2D to any actions that the others can reasonably help him with. It’s a big power boost.

If you’re not doing that, and having opponents act separately, they do just that. The two opponents each engage and position against the single guy. And that guy’s at a big disadvantage, because he can only target one with any given action, and critically any defensive action except Avoid only protects against one foe. If two opponents Strike one’s probably getting through unopposed, and that’s scary.

Avoid works against all attacks on that action (Block only works against one)

Multiple Opponents (459-460) especially the Three on One section gives information about the way multiple attackers can negate their targets advantage for weapon length.
It also states that “Once engaged in this fashion, all opponents may act against one another so long as they use the appropriate disadvantages according to their weapons on the Advantage and Disadvantage table.”
I take that to mean that the multiple opponents modifiers are applied to the engagement test to determine Fight! Advantage but afterwards it reverts to normal as far as weapon lengths are considered.