Lancer is a DD with both Party Status Buffs and Enemy Debuffs.
Lancer is meant to build up TP as fast as possible then drain it into moves such as. Doomspike (which requires 2000TP However you can pump ALL 3000 Into it to do MORE DAMAGE)

Some party status buffs or debuffs that help the party kill the enemy.

Comrade in Arms - Bolster morale, inflicting the target with an enfeebling effect which grants attacking party members enhanced TP generation

Twisting Vice - Stab and twist, dealing piercing damage and wiping out the target's TP.

And a 2 great buffs for the lancer which also affect the party!

Speed Surge - Wield your weapon deftly, increasing stamina regeneration. Hitting the target inflicts an enfeebling status which grants attacking party members the ability to absorb HP.

Life Surge - Make sport of an enemy, granting yourself an enhancing status which grants the ability to absorb HP. While active, successful attacks reduce the target's evasion.

All in all I LOVE LANCER!! I am ranking up other jobs however. THM has more debuffs for my lancer such as all the absorb spells. Those are wonderful!

I agree with most people in this thread that feel lancer is a DD Buff/Debuff class.

I do not feel Lancer should ever be a tanking class, it is a unique DD class and I love it!