Pretty much all been said but yeah, using STR accessories and sword oath you get decent damage. Using fight or flight is also a great boost every DD would kill for a free +30% damage.
There is absolutely nothing wrong with PLD's survivability. I have yet to come across a regular FATE boss I can't kill solo (or at least last til time is up) stoneskin takes quite a few hits to break and you can pretty much keep it up indefinitely with riot blade. If you ever do find your health has dropped to critically low levels, shield bash > stoneskin > rampart > convalesence > cure spam til you feel safe then bloodbath and riot blade to keep your HP up while recovering the MP you used. Bulwark is also a great skill, decreasing incoming damage while also giving you access to a decent damage attack that prevents the enemy using any skills.