It is worth noting that Wedge also increases the damage taken, so it's usually used on cavalry that can charge and skip through a line of damage. Infantry move slower, so they'd theoretically get picked apart as they march in a wedge.
It's also useless defensively (cavalry are pretty much never used defensively) due to that reduced defense and the likelihood that you'll be fortified. BM also doesn't seem to really allow for counterattacks in a single battle (at least tactics-wise), so using a bunch of offensive settings for a surprise turnaround doesn't really work.
Depending on the level of the fortification, the reduction in defence once boosted by the fortification could well be offset by the damage bonus. It would largely depend on the situation, the opposing forces etc. The problem with any statement like this is really the extent of the bonus and penalties is not known. Is it percentage based? If so it would affect low armour units more then high armour units. A unit with 90% weapon and 30% armour may well see a significant increase in its attack, but a much lower decrease in its armour. Conversely if it is a fixed penalty, high armour units might not see much of an effect to the reduction at all. I much prefer to make selections based on what is logical to my character based on the situation they are faced with.
