Bladers lvl the slowest.
In pvp they are the hardest to kill, but hardly kill same lvl people (takes time, or can sometimes even be near impossible).
A blader's duel at high level, if balanced, is very boring.
In group pvp their job is to attract people's attacks while the int guys nuke.
If there is a strong char, they can kd him for a few minutes, giving time for backup to come
Useful indeed.