A "weakness" criterion. This is similar to the rank-by-problem criterion, but rather than ranking on an actual structural problem, it ranks on a structural weakness. This is suitable for things like adjective endings and truncations, where the weakness isn't on the same order as a "problem" but where we'd still rather avoid the weakness if we can.

The point of the separate "weakness" criterion is that we only allow weaknesses to come into play on pass 2, after we've already discriminated based on problems. If we can discriminate based on problems, we'll do so in pass 1 and won't even get to pass 2; we'll only discriminate based on weakness if we can't tell the difference based on real problems.

class CommandRankingByWeakness :   CommandRankingCriterion