Hello,
first a disclaimer: I’ve only had a few chargers and none too successful. They’re tricky and I didn’t like them enough to bother learning how to play them well. That aside, I can tell you about mechanics.
Blessed hammer works only with Concentration, that’s true. Fanaticism works with Charge, there’s no reason for it not to.
The point is that you are missing benefits there. The stronger aspect of the Fanaticism aura is its attack speed, which does NOT work with Charge as it has a fixed attack animation hence is not affected by attack speed. In short, if you’re only using Charge, you can pick the highest damage weapon, no matter how slow it is and completely forget about Increased attack speed modifiers on your gear.
On the other hand, Might is a synergy to Fanaticism so you might use it instead, as it will already be maxxed. Its damage bonus is lower, but Charge gives you plenty already, so will be overkilling mobs. Those are 22 skill points that you can redistribute if you wish (20 Fana + 2 prereqs).
Keep in mind that Charge is a physical damage attack so you will need some alternative to kill Immune to physical monsters. 1 pt in Sanctuary will be enough to deal with Undeads (Sanctuary breaks physical immunity of any Undead monster), which are normally encountered first, so you can use it before you have your alternative attack up and running. I’d personally use something like Holy Shock to deal Lightning damage (double immunes: lightning + physical will also often be ghosts or skeletons so you can still use Sanctuary there) with a fast-attacking weapon on switch, as offensive elemental auras don’t care about your weapon’s damage and they’re all about speed. A Crescent Moon Phaseblade would be perfect for the occasion (fast and lowers lightning resistance of enemies).
A note about Charge playing style: you pick an enemy which seems kind of separated from its pack, slay it, and move on to the next. Be very mindful of the sequence in which you pick your targets. Charge requires an initial separation between you and the enemy, so if you end up being right next to the target, you will produce a weak and possibly slow normal attack, during which you might die. Trying to always have separation is basically trying to position yourself a bit like a ranged character and then dashing left and right across the battlefield. Extra fast monsters will get on your nerves a lot.
That being said, you also need to make a HUGE decision about whether you are going to use a shield or not. A paladin without a shield feels weird, naked, and squishy and turns Charge into more like a ranged attack since you will also have to think about not being hit.
Using a shield adds safety at the cost of Charge damage (you might not one-shot mobs). It will also improve your (1pt Zeal)+Holy Shock switch. On the other hand, you might just use Charge either with Might or Holy Shock, depending on the enemy, forget about weapon switch and use a big bad 2-handed weapon (Crescent Moon fits into 3 Socket Axes/Swords/Polearms, 2-handers included, although its physical damage is not the highest).
Obedience + Holy Fire instead of Crescent Moon + Holy Shock seems like a good idea for a 2-hander on paper, but I strongly suggest to crunch some numbers first. Holy Fire ends up being underwhelming in terms of damage and there are many more fire resistant mobs in hell that there are lightning.
What’s fun is that if there’s nothing behind the mob to stop it, you will just keep charging at it as you knock it back with each hit, leading to its inevitable doom. Really feels OP 
I just might give my 2-handed charger a second chance and build a 1-hander+Shield. After all, to me Diablo is all about trying new builds and making them work.
Long story short, it’s a tricky build to play, probably not the best introduction to paladins, and maybe much better for PvP, but I have 0 experience there.
Hope that helps
