In terms of the mediaeval cultures I know best, those two characters are overlapping, so this is something of a challenge. However, I wonder if something ring or disk shaped might work for A: it conveys totality and balance, and if could reference essential matter if it was also, say, some kind of stone (my instinct says flint, as that is a very early tool-forming substance and thus an early nexus of society and social order). Or something like the triskelion patterns that turn up on a number of megaliths -- picture here: http://en.wikipedia.org/wiki/Triple_spiral It's referred to in that article as 'Celtic', but that's highly debateable, given the dates.
The double-headed axe is a fairly common symbol associated with justice: could that work for B?