This is one of my Black mage runs

I don't have any currently saved of warrior but I'll throw a match up when I have time to do one.

Black mage is all about smashing people with fire and putting dots on them. The electrical burst doesn't hurt and it puts a shield on you but I wouldn't be breaking formation to do it cause BLM is a massive prio target.
The BLM Ice I use on enemies that are running away, or in a choke point. If we're outnumbered, setting an AoE Bind/Stun on a lot of people will force their natural reaction to back up or disengage. BLM does best when the melee and Tanks are playing aggressive and not cowering behind the ranged.

There is really no point in doing guides since all the jobs are going to change in 7.1