I will say that on the lancer forum on lodestone, it seems there may be a soft cap of 250 depending on how many points you have in the other damage modifiers

Basically, someone parsed at 250str and then maxxed str and found little difference, making them think there is a softcap depending on what points you have in other stats, but nothing's conclusive yet I don't think.

Edit: Found the post!

would just like to go on the record that increase my STR beyond the 250 mark has resulted in almost neglegable gains. I think we might have to start looking at the possibilty of there being a fairly stiff soft cap on these stats now. Against Ifrit increaing my STR from 250 to 291,

I gained no increase in AA dmg

Doomspike Crit went up 20 points

Nothing else went up noticeably. i think we need to consider the fact that Piety may play a stronger role than we think and start experimenting with other stats as well.Silvano Conri

Ah I see well with the gear I suggested (with no materia) and Dex +23/Pie +22, I'm at 253 Dex and 243 Piety. At that point I could put in materia or stat accessories to augment Strength/Attack Power/Piety/etc….Arcell

Nice. I wasn't sure where your guide put you stat-wise; figured I'd post some semi-relevant info ^^