In the same idea of replacing Martial Arts with warlord stuff, I'd to something like this:
Level 1 Battle Harmony:
- Once per turn, when you take the attack action, you can use a bonus to grant an ally 1 more attack on its next turn.
- Once per turn, you can use an bonus action to grant a ''inspiration die'' to an ally within 60' that see or hear you.
Level 1 Inspiration Dice (ala Bard)
Lvl 1 Inspire Vigor
As an bonus action, choose a target that see or hear you within 30'. The ally regain 1d6+4 hit points to it, plus additional hit points equal to the creature's maximum number of Hit Dice. The creature can't regain hit points from this feat again until it finishes a short or long rest. (**could be Temp HP instead, depending on where you stand on martial healing). You can use this feature twice before needing a short rest.
Level 2 Shared Assault
Your mastery of battle tactics allow you a better control over the flow of battle. - Once per turn, you can use a bonus action to roll an inspiration die. You gain Command point equal to the number you rolled.
- Group Flurry: When you take the attack action, you can use a bonus action to spend 1 command point to grant two allies 1 more attack on its next turn.
- Defensive stance: As a bonus action, spend 1 command to allow an ally to take the dodge action as a reaction.
- Quick formation: As a bonus action, spend 1 command to allow an ally to take the dash or disengage action as a reaction.