For 1H Sword skills, is Slash really needed? Although it has a fast cast, its weak! According this this guild, I dont need it:
"Slash: A quick blow, nearly instant cast, has a 50% down attack increase. I did not bother getting this skill, it does much less damage then the chains you get, but its probably worth leveling this skill to ~36, but once you have double stab/shield trash/Berserker you won't have times when you cannot attack."
So would it be worth deleveling it? This skill takes a lot of sp, and ive just calculated I need 150k sp to be FF to 90 (even though I farmed 420k sp at Ong)

Also, are there any other 1H or 2H skills that arnt necessary?