4x the static stat bonus (double two stat bonuses), using a combination of encounter/daily resources and partly from a fighter paragon path, in fact it's 5x with Holy Strike.
It looks like this at 14th with appropriate magic gear:
Ardent Vow (minor, +Wis damage to next attack)
Channel Divinity: Divine Strength (minor, +Str damage to next attack)
Furious Assault (+1W on a hit, free on a hit)
Martyr's Retribution (standard & spend a healing surge) +20 vs. AC, Damage 5d12+25 (+6 Str +5 wis +3 magic, +11 from the above), half (4d12) on a miss, target subject to his crappy Cha based divine sanction for 1 round.
It's a decent attack, but not insane for the level and drains quite a few resources. The avenger in the same group is routinely getting damage in the low 100s on his crits and the rogue can pull off this sort of damage with an encounter. If anything it's an overpowered fighter paragon path, rather than the paladin build that's the problem.
[sblock]====== Created Using Wizards of the Coast D&D Character Builder ======
StrikeyPal, level 14
Half-Orc, Paladin, Pit Fighter
Student of the Sword: Student of Two-Handed Weapons
FINAL ABILITY SCORES
Str 22, Con 11, Dex 16, Int 9, Wis 20, Cha 12.
STARTING ABILITY SCORES
Str 16, Con 10, Dex 13, Int 8, Wis 16, Cha 11.
AC: 30 Fort: 24 Reflex: 21 Will: 23
HP: 104 Surges: 10 Surge Value: 26
TRAINED SKILLS
Religion +11, Insight +17, Intimidate +15, Endurance +12, Athletics +16
UNTRAINED SKILLS
Acrobatics +8, Arcana +6, Bluff +8, Diplomacy +8, Dungeoneering +12, Heal +12, History +6, Nature +12, Perception +12, Stealth +8, Streetwise +8, Thievery +8
FEATS
Level 1: Weapon Proficiency (Fullblade)
Level 2: Weapon Focus (Heavy Blade)
Level 4: Mighty Challenge
Level 6: Focused Expertise (Fullblade)
Level 8: Power Attack
Level 10: Student of the Sword
Level 11: Untiring Virtue
Level 12: Heavy Blade Opportunity
Level 14: Honored Foe
POWERS
Lay on Hands: Ardent Vow
Paladin at-will 1: Ardent Strike
Paladin at-will 1: Holy Strike
Paladin encounter 1: Radiant Smite
Paladin daily 1: Blood of the Mighty
Paladin utility 2: Bless Weapon
Paladin encounter 3: Strength from Valor
Paladin daily 5: Martyr's Retribution
Paladin utility 6: Shield of Discipline
Paladin encounter 7: Force of Arms
Paladin daily 9: Knightly Intercession
Paladin utility 10: Righteous Indignation
Paladin encounter 13: Zealous Smite (replaces Radiant Smite)
ITEMS
Winged Layered Plate Armor +3, Bradaman's Fullblade +3, Javelin (5)
====== Copy to Clipboard and Press the Import Button on the Summary Tab ======[/sblock]EDIT: Were you talking about 4W?
The 4W level 1 paladin daily does nothing on a miss, rather than half (this is the real drawback, not the piddly 5 damage).
Both strikers who use big weapons and want big damage in one hit get sweet bonuses on top of their 3[W] (half on a miss) level 1 dailies (Barbarian rages and Avenger's effect powers). I think a basic 4[W] is in line for what they can do (and expect to possible see one with the two-hander ranger build), but I'd guess the designers were going for making powers that were sexy rather than just put out big numbers (though with damage bonuses from the rage/effects you'll actually end up ahead if you use these well).
Rangers get a 2[W] with two attacks right at 1, which is better. 4d12 with two waraxes, half on a miss and double the static bonuses, plus better odds to trigger quarry.
So I can't see a 4W attack with two drawbacks breaking any sort of mold. In fact it looks about right for a off-striker at 1st.
The level 5 costs a surge. This was a pretty steep cost back when all Paladins had lay on hands, but for an Ardent paladin it's not a huge deal. So it may be a little overpowered... The next one is at 15th by which point 4[W] isn't such a big deal.