What would the balance implications be of removing the spell school restriction of learning spells for Eldritch Knights and Arcane Tricksters?

Question

Both Eldritch Knights (a subclass of fighters) and Arcane Tricksters (a subclass of rogues) pull their spells from the wizard spell list, albeit in a limited way. The way in which they do this is by only being allowed to choose spells from the evocation and abjuration schools, in the case of eldritch knights, or from only choosing from illusion and enchantment, in the case of arcane tricksters. Both classes also get very small amounts of any spell they want from the wizard spell list.

How unbalanced would it be to allow both these subclasses to choose spells regardless of school from the wizard spell list? Good comparisons may include comparisons to half casters, and of course to changes in how these classes could play.

Answer 1

I'm repeating the same answer I gave on a previous question which I'll link to this one, but I think it still holds:

The DMG has a Workshop section for customizing your game, and one of the section is on "changing spell lists". It says (among other things) that:

Modifying a class's spell list usually has little effect on a character's power but can change the flavor of a class significantly.

So really, there should be no problems doing this from a power perspective. Your class might play a little differently if you pick thematically different spells, but that is to be expected.

You can find this section on page 287 of the DMG.

In this case, the impact is likely to be even less on the power side, because both of these classes already get a few free picks from the entire list, so any single spell they might have under your rule is already available.

This will almost certainly be a flavor change only.