[Homebrew] Swapping out one part of a class path with another

[Sir_Chivalry]

I have a player who's interested in playing a bard/warlock and they've shown interest in both College of Glamour and College of Whispers. However I'm wondering if I could swap out the psychic blades of college of whispers and swap in the enthralling performance of College of Glamour and have all the things the player is interested in . . . without completely unbalancing the character.

Am I in for a rude awakening as a DM if I allow this?

Is this in general a bad idea with characters, opening myself up to min/maxing?

[Man_Over_Game]

I say do it, with the caveat that you'll be closely watching the group dynamic and whether or not it makes the change unbalanced in combat or in RP situations, and that you'll throttle it back if it gets out of hand.

It wouldn't be overpowered, I think, but the main concern is that each Bard at level 3 is supposed to have some form of addition to their combat utility that uses their Bardic Inspiration. You're completely leaving out that design aspect. Balance-wise, I think it'd be fine, but it's a heavy nerf to Bardic Inspiration.

[Sir_Chivalry]

Would it be better to shift over Mantle of Inspiration as well and move aside Words of Terror then? Or trade like for like, so Entralling Performance replaces Words of Terror?

[Man_Over_Game]

Would it be better to shift over Mantle of Inspiration as well and move aside Words of Terror then? Or trade like for like, so Entralling Performance replaces Words of Terror?

Removing Words of Terror kind of voids the point I think the player might be going for with the Whispers subclass, but replacing the psychic damage for a team buff doesn't make much sense either.

Each Bard subclass has one passive/RP bonus and one use of Bardic Inspiration for combat purposes.

A few things you can do:

Use the RP element from Whispers with the BI use of Lore, to create a master of tricks and lies.
Use the RP element from Whispers with the BI use of Glamour, to create a master manipulator (convincing allies to fight better).
Use the RP element from Glamour with the BI use of Lore, to be a charmer of fate itself.

Or some combination like that. For the most part, they're mostly balanced. The RP use of Glamour isn't quite as good as Lore getting 3 skills, but for the most part it's fairly sane, and won't be any more broken than just going the base Lore Bard.

[Zanthy1]

I think for this scenario it will be just fine. However if you open up this pandoras box, expect other players to have similar requests. Hopefully it's just a coolness thing, but an optimizer will certainly look at it as a way to have their cake and eat it too. Not a bad thing, just be aware of what precedent it sets.

[Sir_Chivalry]

Would enthralling performance be appropriate for a feat perhaps? Just have the player take Whispers otherwise?

Is it too overpowered? Underpowered considering the time required?