The elemental strikes seem fine to me because you get to choose when you land it, which makes it very flexible. Thus it's fine if some are stronger or weaker, so long as the overall package is good.
Unarmoured defense is fine because they're a Heavy Armour class and they normally start with Chain Mail (AC16). At L1, even if you have a +3 CHA mod (which is the most you're going to have, realistically, as it is a secondary stat after STR or DEX), and have Studded Leather, the best Light armour that even exists in 5E (short of magic armour), you only have AC15. If you eventually, at like, Level 12 or something, got your CHA bonus up to +5 (presumably after getting STR or DEX to 20, and likely using most/all your Feats on ASIs), you still only get it with Studded Leather at best, so would have an AC of 17. Still lower than Full Plate (AC18), which most PCs can afford somewhere between level 3 and level 6 (a looooooong time before 12).
The advantage is that you don't get penalized on Stealth Checks, but that's literally it.
That's the option here - Oath of the Noble Genie Paladins can potentially be decent at Stealth - but here's the thing - it's a bit of a trick, because to actually be good at Stealth, they'd need to be DEX-based, and if they're DEX-based? Guess what! This ability gives them no meaningful benefit! Because you have to choose to add CHA or DEX, and as your DEX is likely higher than your CHA, you'd always go with DEX.
You have to get into multi-class-based min-maxing before this CHA-based unarmoured defense is anything but basically a ribbon ability, and even then its questionable given you need to be L3 to get it.