Everything about upgrading skills

Upgrade - eow - silver

+1, 20eow, 100k
+2, 40eow, 200k
+3, 60eow, 300k
+4, 80eow, 400k
+5, 100eow, 500k
+6, 200eow, 1m

For all offensive skills with 90 power
Upgrading +1 to +5 it adds 5power without decreasing its PP. Getting it to +6 making the PP to 3.

For all offensive skills with 120 power
Upgrading +1 to +5 it adds 5 power without decreasing its PP. Getting it to +6 will change its PP to 2.

For iaijutsu and frenzied attack, they have diffirence.
Iajutsu:
+1 = +2power
+2= +2power
+3= +2power
+4= +3power
+5= +3power
+6= i dunno

I havent tried upgrading my frenzied to +2.
Frenzied attack:
+1= +1power 

All skills that have 90power with 5pp if upgraded to +6 will be 120power and 3pp

120 power with 3pp and if upgraded to +6 will be 150power and 2pp

I dont have idea about those AOE skills and other supplementary coz i havent tried one.

From what ive seen AOE skills vary sometimes with +2 dmg

[Koenaj]

I know you can't upgrade skills before Level. 50, but is that the ultimate level for upgrading?
Or does +2 recquire Level. 52, +3 Level. 54, et cetera?

I know you can't upgrade skills before Level. 50, but is that the ultimate level for upgrading?
Or does +2 recquire Level. 52, +3 Level. 54, et cetera?

Yes you are right with this.

[Koenaj]

Yes you are right with this.

Thought so, thank you for confirming it !