blader really gets better after the first debuff (lightning) chain at lvl 73
(or even with lvl 71 (flying stone smash if you take the smashing series))plus they are much harder to kill than bowers.
knockback is the ultimate suspense killer, but it is a bowers only shield (unless they have a real one on the for knockdown situations

)
if you concentrate on taxis(have a friend to taxi you would be best) or find autoshare pts to grind in, lvling wont be a thing, just have to farm alot more than a bower and yes, you will lvl slower.
blader if you can afford to farm more
bower if you want to reach a higher lvl quicker