Back on live Invoke Fear seemed to work better for my SK.  I don't know though, maybe it was crap too.
As mentioned some spells have modifiers (Heat Blood series, Taps, etc).  Fear I'm sure doesn't have one or might even have a penalty as the effect is pretty amazing.  
After leveling a Rogue and SK in live and now a Necro on P99 I think the resist rates are just fine for them, or at least not noticeably bad.  Any easier and it would be hard to call it, "gaining experience" 
[You must be logged in to view images. Log in or Register.].