The wiki smiting build is underpowered because it focuses it's attacks around stonesoul/holy strike, which require you to be in melee range. Mending is unneccesary, as is having any healing prayers if you want to go full on damage.
Here's the build I've been running for a good 8 months now for high end PvE:
*Attributes*
Smiting Prayers: 16
Inspiration Magic: 12
Protection Prayers: 4
*Skills*
1: Signet of Judgement [E]
2: Bane Signet
3: Mantra of Signets
4: Mantra of Inscriptions
5: Smite Hex
6: Purge Conditions
7: Ether Feast
8: Rebirth
*Equipment*
Smiting Rod with 20% Recharge of Smiting Prayers Skills
Jeweled Chalice with 20/20 HCSR
*Theory*
First, allow the assigned tank to gain aggro, then initiate Mantra Of Signets. Activate Signet of Judgement on a foe in melee combat with the tank, it will instantly recharge, allowing you to reuse it. Do so, but be sure to activate Mantra of Inscritions before Signet of Judgement finishes. Follow this up with Bane Signet, then if the tank has been hexed, Smite hex, or if anyone is suffering from condition(s), Purge Conditions. If you attract aggro, use ether feast to heal for over 120 health, as well as cause minor energy denial to your target. Skill 8 is a no brainer really - once the initial energy voley is spent, there is no huge use for your energy pool, so you can potentially cast rebirth during a fight without any huge problems, as long as there is sufficient distance between you and your foes.
*Advantages*
Poweful opening volley.
Holy Damage from skills ignores armour.
Double Damage vs Undead and Summoned Creatures.
No weakness to enchantment removal.
No need to get any closer than the edge of the aggro bubble.
Hex and condition removal.
Allows flexible use of Rebirth, due to low energy usage.
Ether Feast negates need for investment in healing prayers.
Signets are not spells, therefore:
*Hexes like Backfire have no effect.
*Skills that specifically interrupt spells do not work.
*No energy cost.
*Dazed condition cannot interrupt signets.
*Disadvantages*
Primal Echoes can be painfull for a build like this.
Low Defence overall.
Only one healing skill, cannot target allies.
Knockdowns reset enemy aggro.
1 point of Divine Favour - a token effort really
*Practical Use*
I'm by far most at home in a full size Fissure of Woe team when using my smiter, although it's equally fun in smaller groups, (Yesterday's group, which shrunk to 4 people from 8 yielded me a Black Dye, a Ruby and 3 gold items.

)
of course it's most fun when you get to the skeletons, but the knockdown is equally useful on shadow monks, smoke walkers, etc, etc. It isn't as powerful over a short period as, say, the Nuker with meteor shower, who left 5 minutes after we started, but then, I don't need to deal with exhaustion and can cause more knockdowns per minute than him. Then again, when you do get to the skellies and your opening salvo does 4x156, followed by another 4x156, potentially followed by another 180 off smite hex, you can potentially finish them all in a matter of seconds, leaving a few stray targets, which as per my experience is no trouble for a WoH monk, a Domination Mesmer, an SS Necro and the smiter's ordinary attacks. (On that front, I do have a 20% Deathbane staff specifically to use during my downtime, which helps a lot - I've been hitting up to 50 vs the icehands and ether breakers since I got it.)
Oh, by the way, Kiting is what dictates if you live or die running this build - if you're not casting and something comes after you, run like a headless chicken until you can knock it down and move on.
Well, there you have it, naysayers are free to pick holes in it and call me a, well, whatever they want to, but I know what works, certainly for me and my guild anyway. I hope you get something useful out of it though. And in my opinion, it is vastly superior to the wiki build that has been previously mentioned.