Here's the thing. When you think about flavor, you have the whole of human history at your disposal. Even if you stick with Dominion's medieval theme (which you don't have to) there are limitless possibilities. You've got the whole worlds of zoology, botany, metallurgy, leatherworking, chemistry, agriculture, and warfare. You've got landscaping and trinket-making and mining and civil engineering. You can delve into academia or politics or society, deal with the nobility or the working classes or criminal masterminds. You can edge into fantasy with mythical creatures and magic and heroes and villains. There are myriad roles and professions and accoutrements of all the world's cultures and religions and artifacts. No matter what you want to do, there are hundreds if not thousands of great people or places or things that fit the flavor.
The game of Dominion, however, is teensy weensy by comparison. Basically all you can do is manage your deck, earn coins, and accrue points. And interfere with your opponents' ability to do those things too. You've got 4-5 vanilla bonuses, and you can move cards in different ways between a limited number of places. That's it. And most of the interesting ways to combine these things have already been done! I do believe there is plenty of room left for fan cards, but they're almost all variations on existing themes rather than wholly new ideas.
What I'm getting at is that if you've got a particular Dominion mechanic that you want, you should have no problem at all finding a name with great flavor for it that reflects the concept. This is not, and cannot, be true if you go the other direction. Because the entire world and all of human history is a pretty wide net, it's necessarily the case that many possible names and flavors -- probably the vast majority, in fact -- will not make a great flavor match to any good Dominion mechanics.
Understand, I don't fault anyone for arriving at a great Dominion card by starting with the flavor. A great Dominion card is a great Dominion card, period. But if you start with the flavor and wind up with a great Dominion card, you got lucky. And to design cards that way as a matter of course is probably foolhardy and doomed to failure overall. Because some concepts cannot make great Dominion cards. What's liable to happen is exactly what's happened here: you struggle to find a mechanic that fits the flavor, go through many more revisions than most cards ever see or need, then find something that's interesting but flawed -- something that might be improvable, but won't be, because you're constrained by the arbitrary flavor parameters you set out for yourself at the outset.
But find a great Dominion mechanic first, and you can pretty much guarantee that there are great names for it out there somewhere. You might have a hard time thinking of one, but you never have to worry that the problem might lack a solution.
Ultimately, if you really want to start with the flavor, by all means, do it. Why shouldn't you? But don't mistake that path as being an equally legitimate way to design a great Dominion card, and don't expect your fellow game designers, whose opinions you've solicited here, to be behind you on that path.
