On every card, you should capitalize "Honours" in the text below the line (and anywhere else you mention it as a type, e.g. in Fayre).
Gold Trophy -- All official cards either do everything right when you play them, or they use a "while this is in play" clause, or they specify a future time (most notable being Duration cards, which specify "at the start of your next turn"). It's easy to understand how you intend it to function though, so maybe it's still OK. sudgy's wording uggestion may be a better thing to do though.
Copper Trophy -- Should read, "You may trash a card from your hand. If you do, +$1." (PPE: scott points out an alternate interpretation, in which case it should use a "while this is in play" wording.)
Exhibition -- Same issue as Gold Trophy. Actually a little worse. With Gold Trophy, at least you know that the condition should be evaluated in your Buy phase. Exhibition has some strange timing issues though. Suppose you enter the Buy phase. Can you take a coin token if you hadn't yet played any duplicates? Some might say no -- since your turn is not over, you might still play duplicates; you can't check the condition until the end of your turn. But others might say that you can if you don't play any more Treasure (or at least, no duplicate Treasure). It is kind of awkward.
Benefice -- This is an incredibly narrow card. It will only ever grant +1VP in a game with Black Market. Perhaps you mean to do another "future" condition, in which case you need to be extra careful with your wording.
Shire -- A single VP card? Ehhhh. Will elaborate more on this below.
Call to Arms -- Should read, "You may discard a card. If you do, each other player discards down to 3 cards in hand."
Overall -- the concept is interesting, but there are issues. One is that they are not actually self-balancing. Hypothetically, imagine that we have a stack of Victory cards with the same pricing mechanic as your Honour cards. One of them is worth 100VP. The others are worth different amounts all less than 10VP (maybe some are negative). OK, that first one is the most expensive, but it is also massively better than the rest. Hopefully it is clear that this is not at all balanced.
With your Honour cards, the balance between cards is much closer. Nonetheless, there will be boards where one particular Honour is just much better than the rest.
That isn't to say that the idea isn't workable. Knights can have similar issues (e.g. Anna on a board with no other trashing). But the issue may be exacerbated with these Honours because 1. they are all available, unlike Knights where you don't get to pick what's on top; 2. they are all actually quite different, whereas Knights all share the same main attack function; and 3. Knights have a bit of a mitigation mechanic in that they can trash each other.
So this is something to keep in mind. Just because the cost will go down doesn't mean that the cards are balanced. The one single VP card stands out to me as particularly prone to imbalance. The Honour cards do not seem super strong in general, but they are all cantrips so they are all quite safe to pick up. I imagine that quite often a good play will be to pick up that Shire early and then use it to gain all the other Honours for a sweet 10VP. Opponents could respond by buying the cards themselves, but if none of them are powerful for them then it just slows them down in the long run. The Copper gaining from Shire is usually a penalty, but on some boards it is not. Eh, maybe it isn't really a big deal, but it just strikes me as something to be wary about.
One more issue is how much time will need to be spent reviewing each of these cards, especially for newer players. They are fairly diverse and since they are all available to purchase, a player may feel compelled to review every card when they buy. That's a lot of reading to do. With Knights, players only need to check whichever one is on top.
Oh, for the purpose of TfB cards, you need to specify an actual cost on the card. The simplest way to get the same effect is probably to cost it as 0* and have it read, "this costs $1 more for every 2 Honour cards remaining in the Supply."
