Guild Wars 2

I play wvw with like 4 character, and is rly hard to keep them with a good lvl so I can get the wvw skills and bonuses from the new ranks.

It’s like extra levels above level 80, specifically for wvw. Naturally levels on your character aren’t account bound, so that would likely be why.

Why pvp lvl is account bound?

That’s a rank, and doesn’t affect your stats, as in pvp you are automatically level 80 and all gear has the same level of stats.

The wvw ranks give you extra abilities and more strength within various situations, thus more directly similar to the character gaining levels.