I’m gonna give a very non-canonical answer here.
I’ve always thought Tier is a bad abstraction and deos not fulfill its purpose. Summing up scale, money (and Equipment quality), training in only one number is good for listing the factions in a table, but it poses (at least for me) more practical problems than it gives solutions.
So I got rid of it. Or rather, I analyse the description of a faction I use and give it two numbers, each from 0 to 3, so the addition gives a 0 to 6 number, as for Tier (but the result would not always be the same number as the original Tier). Those numbers are: Size and Quality (which derives from how rich the faction is)m which are what is important in play.
Size: Small gang, medium gang, big gang, huge gang
Quality : Poor, normal, Fine, Exceptionnal. It’s more realistic than having seven level of quality in the same setting.
So say, the Red Sashes have Fine Swords and Training but they go by small teams, so that’s why they are Tier II (0+2). Their bosses will be Sword Masters, so Exceptionnal, but it does not raise the whole faction. While the Skovland refugees can assemble mobs (huge), but with only Poor Equipment, so they are 3+0= Tier III (some mob leaders will have normal or even fine Equipment). The Imperial army can field whole battalions (huge) and has the best weapons, so 3+3=VI, good, but does not when three drunken soldiers get into a bar fight, even with their standard regulation sword (normal), of course they are not so powerful.
By dividing Tier into playable concepts, it makes it easier to manage.
The PCs are Tier 0 at the beginning, even if they have one fine piece of equipment or two. So they don’t really go by the numbers I described, but hey, they are the fragging heroes. When you play, the four levels of size and quality is more than enough to do a realistic fiction, more in fact than the unrealistic Tier abstraction.