Help creating a Paladin item!

[Specter]

So I'm having trouble coming up with an exclusive item for the Paladin in my group (level 12). This is what I've got as final so far:

HELM OF THE MARTYR
Wondrous item, very rare (requires attunement by a paladin of good alignment)

This golden helm is devoted to protecting the pure at heart. When you are wearing this helmet, you gain the following benefits:
- You can cast the cantrips, resistance, sacred flame, spare the dying and thaumaturgy.
- You can cast the warding bond spell at will, without material components.

I want to push this into the 'very rare' department, and I want to add something else. These are other features i've been considering:
- Resistance to necrotic damage
- Treating 1s and 2s as 3s in a smite
- Taking damage instead of someone else as a reaction (fits the theme, but maybe steals the Abjurer's thunder?)

Any suggestions are welcome.

[KorvinStarmast]

HELM OF THE MARTYR
- Taking damage instead of someone else as a reaction (fits the theme, but maybe steals the Abjurer's thunder?)

Any suggestions are welcome.
That's the the most thematic of your additional ideas. Roll with that and No, it doesn't steal the abjurer's thunder. See also Warding Bond and Protection Fighting style.

Regarding suggestions:

Add anyone trying to wear it who is not of good alignment takes 4d6 radiant damage

Alternatively

Anyone trying to attune to it who is not of good alignment takes 4d6 radiant damage.

[Foxhound438]

I feel like the best thing to do is expand the spells it gives. Maybe add in find steed (fits for paladins), spirit guardians, aura of vitality, aura of purity, aura of life, and mass cure wounds. Yes, I said "and" there, as in all of those. Very rare magic items are apt to cast spells up to 8th level after all.

Obviously most of those should be limited to some degree- maybe have the good old fashioned 7 charges with recharge 1d6+1 per day, and each spell costs charges equal to its level?

Another option is to boost lay on hands, by allowing it to be used as a bonus action. Maybe add points, though I would be careful with that, and maybe expand the scope of conditions it can clear- in fact, saying "you can use your cleansing touch at the same time as your lay on hands" does just that while also giving the item some interesting scaling that would otherwise be absent.