Obviously Shardwielding isn't Shardbearing, because Shardbearing isn't something that's gone and Shardbearers aren't magical, just have magical loot. So, anyone know what the heck that is?
Actually, I know the answer: we don't know. But I jumped to a conclusion (as I was typing this) from little to no evidence as a baseless theory full of holes suddenly appeared. Note that this contains spoilers for other Sanderson books.
So the theory: There's 7 completely different kinds of magic on Roshar, and we have only heard of 3 of those in Old Magic, Voidbinding and Surgebinding.
And the general consensus (or what I think is the general consensus) isn't necessarily correct: Surgebinding from Honor, Voidbinding from Odium and Old Magic from Cultivation. We know nothing about Voidbinding and Surgebinding seems to really be very closely associated with Honor, but especially Old Magic is troublesome. One boon and one curse Nightwatcher thinks is appropriate for you. What exactly does that got to do with Cultivation? Seriously? OTOH, it looks like a somewhat odd but plausible mix of Honor and Odium.
And going back to the start, there's Shardwielding. And we know there was something called Dawnshards and Almighty mentions that they'd be useful but are gone. Since Shardbearers aren't related to Shardwielding, I postulate that Shardwielding is related to Dawnshards. And back cover can't be lying to us (inconceivable!) so they'll come back at some point. Surgebinding is already "returning". And, I'll make another utterly baseless claim to say that Cultivation's real stuff is those: Dawncities, Dawnchant, Dawnsingers, Dawnpizza...=Language, permentant settlements, (maybe) medicine and healthcare, pizza... They all look like things that could easily tie into cultivating humanity.
We know magic, as general rule, comes from Shard interactions. But nowhere it says the Shards haggle about and draw up laws to govern mortal magics over dinner. My suspicion is that whole magic systems just spontaneously appear every time Shards are close with no conscious effort on their part, thanks to Adonalsium connection.
Furthermore, this would mean that the total number of magics possible in Cosmere is a stupidly large number that I'm too lazy to calculate. That kind of justification would give Sanderson enough cool magics to put in books for several lifetimes.
So there it is. Another off the wall "theory" that was sparked by some tiny thing. Make of it what you will.