|....you unholy mother fuckers...|
The best way I can think of to make them interesting is to basically throw them out and start over with a new divine-inspired race type. Which is what D&D has done before, and what I've done now. I decided to make them a floating sub-race, and having done so I'm surprised why I haven't seen more of these in the DIY community. Humans were slightly tricky, but otherwise most races can graft this on easily and you can explain those who can't with the fact that the universe is sometimes a huge dick. Especially heaven. I'm sure you could take the Power of the Word sub-class feature as a Feat later? Or work with your dm to make your 1/3 human 1/3 orc 1/3 angel thing? But that's your lookout not mine.
As replacements for Aasimar, they do raise the question, why are these many different kinds of angeltouched being but only humans made half-devil-people? The obvious answer is that everyone but humans knew better.
The Word are in fact a sub-race which can be applied to any existing race that has a sub-race. Dragonborn, Half-Orcs, and other halfbreed and mongrel races - those without a subclass - are not shewn the true light of the Word. This is the will of the Word. (For Humans wishing to speak the Word, simply add +1 to any 2 Ability Scores and a Language then ignore anything else you would get for being a Human. You are now the Word.) Those who seek the Word will find the Word, though the Word may not speak to them. Those who hear the Word become vessels for the Word, and endeavor to spread the light and order of the Word.
When you choose to be a vessel unto the Word at character creation, you gain the following benefits:
Ability Score Increase: Increase your Wisdom by 1.
Light of the Word: Your eyes may glow brightly like candleflames as an action. You may extinguish this effect as an action. You may also dim and control the brightness of this effect.
Power of the Word: You may speak the Word as an action, though afterward you must take a long rest to regain your strength. Upon reaching 5th level, your understanding of the Word has deepened to the point where you recover more quickly, and may speak the Word again after a short rest.
The Word is all and eternal, but vessels of the Word are weak and simple. Their understanding of the Word is limited to these expressions:
Faim- You confer resistance to necrotic damage to an ally, and yourself gain advantage on saves against necrotic damage. These effects last until your next rest.
Ilthyk- You confer resistance to radiant damage to an ally, and yourself gain advantage on saves against radiant damage. These effects last until your next rest.
Gilr- You may speak as a reaction to allow another who has used their reaction already to make another reaction.
Mosch- You speak and allow another who has or has nor acted in this round to make an additional action this round.
Padiihs- You may impose disadvantage on a knowledge check, and gain advantage on your next knowledge check.
Rav- Your booming voice communicates a single-word concept to all intelligent creatures within 100' of you, regardless of language.