The growth of trade made feudalism seem pointless because if you are able to trade, you don't need peasants to produce products for you. The hundred years war declined feudalism because there was so much fighting going on and many knights went to battle and there weren't knights in the feudal systems anymore. The bubonic plague acted as a distraction from feudalism. In other words, there was so much chaos caused by the plague, people didn't care about feudalism, they just wanted to survive. And finally, the centralization of the power of kings and churches didn't give the kings as much "rule" as they did in feudal systems, so that kind of defeated the point.
I think lords bringing stability helped barter economy because it helped people feel safer and people could feel like they could trade without being "catfished".
Finding the right person in a barter economy can be very difficult, and probably very frustrating. You would have to find a person that has the product you need, wants your product, wants the amount you want to give, and offers the amount you need or want. It would also be hard in a barter system to evenly divide products being traded. If you were trading chickens for grain, how would you evenly divide them? It's also hard to determine value. As I said in the last subject about dividing products, it''s very similar to finding value of products. Let's take the Chicken for Grain example again. How much grain equals one chicken? That would be something difficult to determine. And of course, capital gain would be a large issue because things weren't organized back then like they are today, so you can see how it would be a struggle.