I'm on my, true ffed, glaive lvl 74 too and I did 50% in like an hour o.o
Could be because I'm on zszc, got a sun+7 glaive and grind on 78/80 mobs but ok
Take a look at this topic:
viewtopic.php?f=5&t=23381It has a chart with the monster hp up to roc. Find the highest mob you can 2 skill and you should be to do more than 1.5%/h