Screwed up my skills, please help

I'd like to start off by apologizing if this is in the wrong forum. I really don't know my way around this site very well.

Anyways, I logged on to my Crusader UA after a long period of not playing and saw that I had 10 2nd job skill points available to put into either Weapon Booster or a skill that was unfamiliar to me, Slipstream. I put in one because I wanted to see what it did, and now I'm not sure which to put my 9 skill points in. According to the skill description, Slipstream goes the same distance no matter what skill level it is and just uses less mp, but then again, booster is the same and just lasts longer. Taking points out of Ground Smash isn't an option because I followed an out of date guide that told me to max it.

Also, I did some research into this and found some people saying that the 3rd job skill Shout is useless. If it is useless, what should I do if I maxed it (again, I followed an out of date guide)? I hope there's some sort of way to get an sp reset scroll if I did something wrong because I don't want to have to spend money.