Polearm 5hit

How much STP is needed for a 5 hit with a Polearm?

Vague.

There you go, assuming you're referring to a SAM 5-hit. If not, then I don't know, that'd be a Raen question.

This depends mainly on what job you are on and the delay of your polearm. For me with 35 store tp from merits and trait and a 480 delay polearm, I only need 20 (iirc) from gear for my 5 hit. So if you are a drg not subing Sam you would need aprox 55 store tp for your 5 hit with a basic 480 delay weapon. And 51 for a 492 delay weapon like thalassocrat.

from: http://wiki.ffxiclopedia.org/wiki/Samurai:_Ultimate_Guide_by_Gregedor

Hello,

You need +19 Store TP from equipments (25 Trait + 10 Merits + 19 Equipment = 54 Total).

13.0 * 1.54 = 20.0

You're not forced to wear that much.
Penta Thrust is a 5-hit WeaponSkill thus the last 4 hits gives 1 TP each.

I suggest not accounting more than 2/4 hits.

Example :

13.0 * 1.51 = 19.6
19.6 * 5 = 98.0
100 - 98.0 = 2 (2 of the 4 extra hits from Penta Thrust)