To some extent it depends on the player but if you're dealing with the challenge of setting things up so you can fully control your character using one hand Black Mage might be a decent option. It obviously still has the same problems of needing to cast and avoid AoEs which melee jobs don't suffer from, but there are a lot fewer skills you'll be using regularly so I can imagine it's quite possible to set it up for one-handed use without needing a lot of clever tricks. I play on a controller so I'm quite conscious of how many different buttons I need to use for each job and BLM is one of the more manageable with its relatively rigid rotation-based play. You will also benefit from having most of your cross-class skills already unlocked since you levelled your SMN/SCH up first (though definitely grab Raging Strikes from Archer when you can).