This combination probably approaches the fighter/ herald for synergy. It’s very possible to get the casting ability of the wielder lined up with the herald, which makes the build just need Strength and Charisma for ability scores.
The real value comes in the form of the nearly insane levels of flexibility this mix provides. You can turn herald spell slots into exertion, artifact charges into exertion, and exertion into artifact charges. That means that unless you’re out of everything, you will probably have the resource you need to do what you want to do on tap, and this is on top of the fact that the wielder has a full-sized exertion pool. The flavor works at least as well as the mechanics do as well; fiction and legend are full of characters like King Arthur and Michael Carpenter who embody knightly virtue and also wield some powerful artifact.
Pretty much any way you build this will play in a similar way; you’ll have a mix of spells and maneuvers and want to get right up on top of your enemies in combat. You can make a case for emphasizing either class or an even mix, but you probably really can’t go wrong here. Pick what’s going to be the most fun for you and go.
[[Synergy Feats for Multiclassers#Herald w/ Wielder|Herald - Wielder chains and ideas]]