Why do tanks exist?

[Avatre]

After some practice, you can usually tell which enemy you're about to lose enmity with based on how low its HP is and when the last time you hit it was.

Could always rotate your rotation so each hit connects with a different target. Might not be the best for downing enemies fast, but helps maintain your enmity. I do that when I tank, and try to make it so the final hit is on a different target than the time I got to that skill last time. CoS as a PLD every time it is off CD also helps(marginally).