I followed True XenoBlade's guide and made the character he suggested.
One thing that I would tell you to learn first is how to actually do a Guard Impact/Just Impact. You need to hit Forward or Back + Guard (A usually) and you should see your characther swing his sword upward. If he guards then you did not do it correctly. You need him to swing to block the incoming attack for to count as an Impact.
It is also very touchy and does require a lot of luck, so I would suggest waiting to get
because you will get quite a few Guard Impacts on the way to getting your Just Impacts.
Where I differ from XenoBlade is where to play.
I sugest you play aracde. I suggest this because you get two rounds vs the computer and you can retry quicker. Where it takes longer to load in the TOLS.
Also in aracde, I would suggest fighting Kilik. He uses a long staff and you can anticapte his attacks better because you can stand further away from him.
Please leave any questions you have in the comments and I will answer ASAP.
Also, if you feel that this guide is not up to snuff please let me know why before you vote negative. Thanks and good luck!