| I suggest mastering both skills. There's not really a lot of skills for a Fox to obtain anyways, since half the other Sense skills are Gun Based for their First Job.
Stone Strike's accuracy is low, but the damage is insanely high. If you can get yourself decent AC equipments, the skill will show it's usefulness. Lv 10 is a prerequisite of a future skill called Lucky Seven (which also requires Lv 1 Armor Destructor). With Lucky Seven (and Aura of Luck for your Second Job), it'll help block enemy's critical hits, allows you to do more critical strikes, and give you a better result when doing a Mature Compound (adding additional stats to your equipments).
Shuriken Master is optional, but usually recommended by most. It's not a prerequisite of any useful higher level skill though. During the lower levels, the accuracy is pretty high, cooltime is low, and the MP cost is conservative. In addition, the long range will help you in survival if you plan to switch to hit-and-run mode.
Both skills are based on DA for it's damage, and AC for it's accuracy. If you want to do more damage, then place all Bonus Points on DA. If you ever need more accuracy, I suggest getting equipments rather than adding points to AC. |