I spent my last big of time trying to puzzle out the stats and math.
There's a positional bonus from weapons. Most are side or back, but sometimes there are weapons with front bonuses. These are handy for soloing of course, but it is hard to figure out what the values do.
There's a HIT value that is really common and I think is sort of a to-hit roll booster. This can boost crits to happen more often. Then there's a more rare DMG value that adds to either min or max damage or both.
I found that 1 hand maces have DMG from the front so I made one. Then I discovered that leather armor pieces convey +2 flanking. Flanking appears to just directly add to any positional bonuses on the weapon. So a +5 DMG on a mace turns into +5 (+12) with a full set of leather.
When you are hitting for like 5 average, adding 17 would be huge, but I tested it and it's more like 2-3.
HIT seemed more valuable, but I didn't really do any rigorous testing. If HIT can bring you in range of hitting reds, that would be super valuable as fighting reds in groups is superfun.
Speaking of that last, they need to bump xp on tougher enemies. Enemies have a chevron by their name. 1 is soloish stuff, 2 is duoish, 3 is groupish, 4 is supertough boss type stuff. Fighting the 3 chevs didn't seem to give any more xp than 1.