Re: SP: Freezadin Weapon?
IMHO it is hard to do better for a general purpose weapon. You'll still want black (or whatever crushing item) on switch for bosses but crescent moon is very nice. Especially if you go back to players 8, that static field will be dandy.
I'm currently using a Gull dagger I'd gotten off NM Meph as my switch weapon together with a Rhyme shield vs bosses. TBH, I do know how well Static proc from Crescent Moon works vs tanker-type mobs with huge HP that aren't lite immune. The IAS bonus coupled with the base speed of a PB will get me a fast Zeal attack, not the mention the ITD vs non-unique mobs. But I'm already packing an almost 10K AR as it is with max'ed Zeal and the other bonuses from my gear, so the ITD isn't as attractive as it would normally be; but sexy nonetheless

.
Obviously something like shael'd stormlash (or grief obviously if you use RWM) is better but not reasonable at your level and gear availability.
I had a couple of Griefs on bnet and used them to good effect. But I doubt I'll be seeing a LO rune drop anytime soon if at all (since we can't trade for one in SP). The same goes for Stormlash, I'd actually never had that drop; ever! even on bnet. Haha.
The only other thing you'd really do with the um is make duress. I suppose duress might last you longer if you luck into a really good weapon down the line, but crescent moon is guaranteed to be a substantial immediate upgrade.
Duress would be great if I had another UM drop. But as it is, I have CB from Goblin Toes, and so far that worked sufficiently well enough. I actually prefer Duress if I'm using Holy Shock as my primary aura, since the cold dmg + that from Ravenfrost will help vs lite immunes. If I were to face cold immunes, neither the cold dmg from Duress nor the one from my Holy Freeze aura will help. Which is why I'm using Lava Gout gloves for extra elemental help (not to mention the sexy 101%AR bonus from Enchant proc) vs cold immunes.
An update of my stats, skills, and gear for any additional advice on how to proceed with a possible weapon upgrade.
Character level: 80
Stats (with gear on)
Strength: 109
Dexterity: 117 (blocks at 73%)
Vitality: 300
Energy: 15
Spare points: 31
Defensive Auras
20 Resist Cold (synergy)
1 Salvation (utility skill)
1 Prayer (prerequisite)
1 Defiance (prerequisite)
1 Cleansing (prerequisite)
1 Vigor (prerequisite & utility skill)
1 Redemption (utility skill)
Offensive Auras
20 Holy Freeze (primary aura)
1 Might (prerequisite)
1 Holy Fire (prerequisite)
1 Blessed Aim (prerequisite)
1 Concentration (prerequisite)
1 Fanaticism (secondary aura for smite & vs cold immunes)
Combat Skills
20 Zeal (primary attack)
12 Holy Shield (utility skill)
1 Sacrifice (prerequisite)
1 Smite (secondary attack)
1 Holy Bolt (prerequisite)
1 Charge (utility skill)
1 Blessed Hammer (prerequisite)
Gear
Helm: Rockstopper
Armor: Vipermagi (has low resist - hoping for a replacement with a better armor)
Glove: Lava Gout
Belt: String of Ears
Boots: Goblin Toe
Amulet: Angelics
Ring1: Angelics
Ring2: Ravenfrost
Weapon1: Aldur's mace with 3 Shaels
Shield1: HoZ with Pdiamond
Weapon2: Gull dagger
Shield2: Rhyme with 58res
1302-1546 Zeal dmg with a level 23 Holy Freeze aura
10.4K AR after enchant
5.1K Def after level 19 Holy Shield
Resist are currently 75/55/55/40
Inventory: 2 Pcombat gcs, 3 100+AR gcs, a couple of random life scs, cube, TP book and ID book, 8 squares of free space.
Edits: I suppose I could respec to a Holy Shock variant if I make Duress, but I'm not really all that keen on loosing the slow effect from Holy Freeze as it can be helpful in staying alive sometimes. Plus my act 1 merc is using Riphook & Blackhorns together with Rattlecage for maximum slowness against mobs as an additional safety feature.