What i find out about Ninja 1st skill , or Ninjustu to say :
Water + Fire = Evasion Wind + Earth = Clearance (trigger when party/mc is being debuffed)/Avoid being targetted Earth + Fire = Double/Triple attack rate up Water + Wind = Dark attack (Shinobi mark for dark) Water + Earth = Poison AoE Fire + Wind = Light attack (Shinobi mark for light)
Same element = Shinobi mark of that element
3x Shinobi marks = Delay (if has cube)/Attack down (if no cube)
fire + fire = fire damage + fire mark fire + water = chance to crit fire + wind = light damage + light mark fire + earth = triple attack up water + fire = dodge water + water = water damage + water mark water + wind = dark damage + dark mark water + earth = damage + poison wind + fire = multi attack down wind + water = overdrive gauge reduction wind + wind = wind damage + wind mark wind + earth = avoid being targeted by enemy? earth + fire = attack power up during blind earth + water = remove own debuffs + heal -50% ougi for self earth + wind = remove 1 debuff from party earth + earth = earth damage + earth mark
I don't know if you want to add this to the guide, but here's what a friend told me about ninja's first skill. One that might seem questionable is the wind+earth one.