In professional sports, it's common practice for teams to trade players. Generally, both teams endeavor to make a trade that is equitable to both (although in practice, it doesn't always work out that way)...either in terms of equally skilled players or monetary compensation of some sort.
Let's say we were to swap wuxia martial arts skills. What would be some good trades?
Here's an example of a good trade: Tai Chi Sword for Dook Goo 9 Swords. Both are excellent sword skills that can serve similar functions, and one is not clearly superior to the other. Each has its unique merits.
A bad trade, obviously, would be something like trading the Hong Lung 18 Palms for Southern Seas Divine Crocodile's scissor kung fu. Terribly one-sided trade.
An apparently good trade that isn't so great, when you think about it, would be something like the 9 Yum Jen Ging for the 9 Yeung Jen Ging straight-up. Both are great inner training manuals, with perhaps a slight edge going to the 9 Yeung, but the 9 Yum has all kinds of nifty external skills whereas the 9 Yeung has none at all. To make this a fair trade, whoever is trading away the 9 Yeung has to throw in some decent external skill such as the 7 Seung Fists or something like that.
So, what would be some good martial arts trades?