Elemental damage charms can be more destructive than Fine SC's on a physical build. The problem is they're hard to find; the highest only drop from Baal & Diablo, but can be rerolled w/3 Pgems.
A Shocking SC of Storms can do 2-99 damage (50.5 ave). Stick that in 26 inventory slots (my usual layout), and you're getting 1,313 average damage. Your Conviction doubles your damage for almost any monster who isn't immune, so you'd be pushing out 2,626 avedam. Compare that to a 26 slots of 3/20s, which (assuming: 70%DS, +2K% damage, 30% EPhR) nets about 975 avedam.
The problem is, again, those are rare! A SSCoS will take about 33K Baal SC rerolls to get. However, my strategy is a little less bleak.
Broaden the charm requirements to include Shocking, Arcing, Flaming, or a Pre/Suf pair (Smoking/Glowing/Hibernal w/ Thunder/Incineration/Winter). Now you'll have a 1:40 chance of rolling one of those mentioned above from a Baal SC. The composite average damage will be about 22 elemental damage per charm. Which means you'll get about 1,148 avedam for a 26 charms. Not too shabby.
The cost? 120 pgems per charm (gotta get Baal/Diablo SCs, first). 3,120 pgems, around 7xBer in SP Trade. Yikes!
I'm actually in the process of doing this for my Kicksin.
Crescent Moon is an okay weapon. It gives you Static Field, which is nice for the first half of monster health. But if you have Conviction, the -35% ELR will only really help you on the immunes you've already broken.
Other options:
Famine: 400.5 Ave Elem Dam
190 Ave Magic Dam, w/ good Physical dam, fast
Hand of Justice PB(synergized): 469.5 Ave Fire Dam
good Physical dam, 20DS, fastest
Gimmershred: 902 Ave Elem Dam
slowish
Azurewrathe: 375 Ave Cold Dam
375 Ave Magic Dam, Sanctuary, decent Physical dam, fastest
Baranar's Star: 300.5 Ave Elem Dam
slow
Stormlash: 272 Ave Lightning Dam
Static Field Proc, 33%CB, decent physical, faster
I'd say it's a toss up between Azurewrathe, Stormlash, & HoJ. Keep in mind, attack speed is critical. All can hit a 4 frame Zeal, but Stormlash needs a lot of help. HoJ requires 40 skill points to synergize. If you can get your hands on an Azurewrathe, you won't be disappointed.