At will help at third level balances against the Hunter's colossus slayer, and it already exists at level seven. But if it's a preference thing, I understand.
All the healing and HP the pet is capable of adds up to less than Lay on Hands from the paladin, and the paladin gets more damage to boot.
in the case of the giant poisonous snake (+6 to hit, 16 AC, up to 17.5 damage, with 10 ft reach! Add on the beast master's +2 proficiency bonus and it goes way overboard). Granted, it only has 3 hp/level, ...

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.