The problem of BL is it's crazy composition of visually highly armored units with armor being weak to a certain extent.To add to this armor has no disadvantages at all, except slowing down a bit on foot, no gaps, no deformable or breakable junctions, no slag, no heat problems, no sight problems. We also don't have special anti-armor weapons which were the result of better armor in the real world. Because BL allegedly takes place in an 11th c., with more or less 11th c. weapons but partly 14th c. armor.
Couple this with the opinion that isolated tests of armor made with modern materials give decisive data for historical armor. Some people think that armor, like mail, made people untouchable and plate was only used later because it was possible and cheap (like Dan Howard, incredible ...). Obviously a lot of battles where higly armored troops were beaten by less or unarmored opponents were historical lies.
The latest tests by Tod et al. showed that plate (made of mild steel) was quite effective against a 160 lbs warbow from 15 yards, and that modern mild steel simulates seemingly better quality wrought iron (most common armor material before the 15th c. AD) quite well. It also showed (again, as there are a lot of tests) the low defensive qualities of normal (not especially thick and heavy special area's) mail against arrows, as well as that less powerful bows achieved not that much less penetration than the 160 lbs bow.
Does this help for BL? No, because in BL we have no realistic armor and health system. We have a system where hp is slowly diminished, and till it is 0, the person is fully functional. So all the amount of damage by hits is arbitrariness. Cloth and mail should not offer great protection, proto-plate armor should be better, but not on real plate level. Wether that does mean 4 hits to death or 8 is a gameplay decision.
I would not mind a decrease of pierce damage effectiveness of projectiles (but not javelins) and an increase of pierce damage for spears and swords. Sadly I cannot mod that in, other than shields for recruits, removal of armor from the troops or removal of Fians from the game. So I have to use RBM with combat module enabled, let's see how long I can suffer through.