The normal values of the axes will scale with level no problem.
But I guess the lash will stay low because it only scales with the Priest's dispositions - if those are in line with their god's dispositions. I suspect that wouldn't work with a non-priest. But I haven't tried. Maybe it works if you character adheres to Rymrgand's dispositions - I mean you can accumulate disposition points as non-priest as well. Just don't know if that gets translated to the axes then. 🤷♂️ Worth a try I guess.
Draining Touch is the most powerful one handed weapon in the game (besides stuff like Scordeo's Edge+Salvation of Time or Wall of Draining or Grave Calling with skeletons and such things)... if you can keep it with the Grimoire switching trick.
Not much comes close imo. The very high base damage, combined with some damage bonuses, leads to hefty dmg per hit, the health draining and the weakening as well as the targeting of Will make it more powerful.
There's a reason why you are supposed to only get one proper hit or crit with it. In combo with a club+modal it's even better.
It's also very good on a Wizard/Monk. You don't need Enervating Blows anymore, the draining is nice to stay healthy (even makes Helwalker less scary) and Swift Flurry + Heartbeat Drumming in combination with Merciless Gaze and the ultra low Will of the enemy from club strikes and spells means that additional attacks will proc frequently.
Or improve the dmg per hit with Lightning Strikes, both options are great. Turning Wheel is also nice in combination with that high dmg per hit. Hylea's Talons add a lash, Baby Boar does so, too.
Wizard can pick Spirit of Decay which grants +1 PEN with the Draining Touch weapon. Add Monk's Thunderous Blows and you are at +3.
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Another nice combo with Wizard and Draining Touch is Steel Garrote. Steel Garrote drains health if you attack afflicted enemies. Draining Touch put weakened on enemies: nice synergy. You drain twice from the same attack which is great for using Blood Sacrifices, you can achieve enormous defense and AR numbers. You will have nice synergy between Eternal Devotion and your spells, too (+15% burning lash to spells, Eternal Devotion works like that). Eternal Devotion's accuracy can get buffed by 10 points with the Ring of Focused Flames. That means that not only do you drop enemies' Will via club and spells but also raise your accuracy by +20 (FoD+10, Ring +10).
If you don't like Steel Garrote then Kind Wayfarer also works nicely. Instead of draining twice you will heal in an AoE with white flames and drain health with Draining Touch. Also nice for Blood Sacrifice. Rest is the same as Steel Garrote or any other Paladin/Bloodmage: Lay on Hands with Wall of Draining etc.
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A brutal combo can be Soulblade/Bloodmage. Citzal's Spirit Lance is awesome with focus gain and Soul Annihilation.
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Bloodmage/Unbroken is also very good: Mob Stance, Kapana Tanga club with +2 engagement, Hold the Line, Draining Touch and Ryngrim's Repulsive Visage as well as an Essential Phantom. Enemies will get terrified and disengage, you and the phantom will deal incredible disengagement attacks with Draining Touch (remember: diseng. attacks get +100% dmg). Mob Stance cleaves are likely to kill enemies on the spot, leading to potential chain-cleaving and so on.
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Bloodmage/Furyshaper: combine Draining Touch with Barbaric Smash, Bloodlust, Bloody Slaughter and most importantly Blood Thirst. Also Carnage profits from the high base damage. Summon a Fear Ward so you don't need to cast Ryngrim's spells. Do similar things like with the Unbroken but at higher speeds but less potent disengagement attacks. Instead of cleaving you will have higher speed and 0 recovery after a kill. Barbaric Smash + Bloody Slaughter does enormous damage if you use it as finisher against near death enemies - and costs nothing if it kills.
Bloodmage/Berserker also works but is very tricky.