Full Str is all you need to know
but to be fussy look below
Bicheon lv80
max all
in the Shield technique series do not level Mountain shield and Giant Shield
in Hidden blade Series lvl Soul blade force to lvl 1 only *
in Sword Dance series lvl Petal Sword dance to lvl 1 only *
Fire is best for str builds lv80
max all fire skills except for Fire Wall series , Flame Wave Series and Fire Combustion Series * (used to see Europe chars under invisible state and stealth state)
Light because you need it for speed and parry lv 80
max all except Thunder force Series, Lion Shout series, Thunderbolt force series
Ice you dont really need this and there is no point in wasting sp to lvl it to 60 but you can lvl it to 30
or you can lvl Force to 30 or another weapon
Full str so use Garments or Protectors preferably Garments
max STR blue on them yada yada i could go on but must sleep hope that helps.
* level the items with star only if you need them, but make sure ya got the Skill points to waste on them.