@Tingyun: I made a separate Feature Request for this one.
What I'd envision happening from this would be that you hardly need to worry about what sword to use anymore.
You may change it if you prefer a different style, but otherwise it'd all be skills.
In an ideal implementation, there would no longer be a huge difference between high-level and low-level characters, other than their actual skills.
A bit like real life, for example.
Getting better armour may help you then to offset a lack of skill.
Bigger guns can be better, so to prevent being able to get those in the early game, they'd have to be expensive which also means it must be uncommon to find them for loot.
Effectively, in the early game (when you have low skills), you may want to avoid fights altogether. Or at least pick only small ones you know you can win.
At some point you become proficient so that fights aren't a huge concern anymore, though they're still evenly matched because there isn't a huge progression.
This is the point where sea battles should be more the focus. And once those become relatively doable as well, you should be ready to get into fort assaults and possibly politics.
That way, instead of the game levelling up to keep things hard for the player, despite the player levelling up,
you get a game progression where you end up doing different things altogether in the later game.
This is something I have suggested for Hearts of Oak as I believe it has some merit.
But it is quite a different approach to the game and I doubt it could be made to work in PotC in a rush....