Nearly 13th-level bard in Age of Ashes here - and playing a 2e bard has been a great time - but not without quite a bit of homework.
I've been playing an polymath / maestro bard - and I'll give you a few things I've learned.
Lingering composition from Maestro is huge for me. 3 or 4 rounds of Dirge of Doom without having to use a action on subsequent turns gives me the option to cast spells and move on those other turns.
At levels 3-7 I got a lot of mileage from heightened fear until I tried using Calm Emotions as my level 3 signature - and that thing **STILL** ends encounters when I cast it from a 5th or 6th level slot. It's incredible and I can't recommend it enough.
Fear also conflicted with Dirge of Doom once I got it - so keep that in mind.
Your hunch is correct regarding knowledge and bards - I haven't found that there's enough impetus to make bard knowledge worth pursuing. It is a lot of effort and feat tax and very little payoff. Combat reading has proven better to me - it all keys off of occultism and it tells me the important stuff. (I think a flaw in the system was that knowledge was intended to be necessary, but it's seldom better than metagaming/guessing and often worthless - but that's a whole other thread.)
You're definitely going to get more mileage from doing buffs/debuffs and battlefield control. I'd say to keep Magic Weapon on 1st or 2nd sig for the time being and consider something like Calm Emotions as a signature also - it's worth the sustain. Also, don't scoff at the power of illusions in this edition. They're definitely worth having in the arsenal.
At 12th, my first three levels of spells are these:
(1)
Lose the Path
Liberating Command
Magic Missile
Soothe(S)
(2)
Faerie Fire
Illusory Object
Dispel Magic (S)
(3)
Calm Emotions (S)
Time Jump
Slow
You'll find that in time you'll need to repurpose your lower level spells for general utility - and the Esoteric Polymath feat chain has been a huge time saver there. As the party gets access to funds, you'll have the ability to grab some scrolls. Don't be afraid to grab one or two of the niche utility spells in case you need them. By time you're out of them, you'll like be richer and in the next town over.
Reading the Bard guides has helped me some - but I've found at points, there were places where our experience differs. Definitely check them out - if not for anything else other than a sense of planning how your character will develop.