I saw someone homebrew second tier manoeuvres that cost two superiority dice and could affect more than one target. It would be easy to do that for warlords too.
Ironically, the banneret is uninspiring and doesn't seem to be a popular choice. If the banneret was given non-scaling d6 superiority dice instead of proficiency in persuasion, giving them the manoeuvres that affects charisma checks and then a choice from the other warlord type manoeuvres, it would take it a step closer to where it needs to be IMO.
In previous editions, fighter-mages were only possible via multi-classing. I always assumed that eldritch knight was just intended to synergise a bit better with that process, not that it was ever intended to reflect the trope on its own.