Record of Agarest War Zero

This achievement requires you to raise your Strength to 50. This has to be the base stat which is the red bar. Item ehances are it green. So what your going to want to do is focus each character to a specific stat or two. After every battle you gain PP that goes into like a team PP bank that's available to use on any of your characters. Just keep saving the PP. Around level 6 you should have enough, probably about 70 -80. Save your game then go into your menu and then press y on the stat tab. Then select Use PP and choose the character you want to enhance and just add the points into that stat till you hit 50 then just reload your game.
Hope this helps!