The best energy weapons are currently rare - so make Energy your no-drop element. Most FO builds also align their Awe special to PWD for that 4% insta-kill chance.
Bloodzerker Sword series from the Rare GGB are functionally clones of the Bloodblade weapons, providing bonus damage to both weapon attacks and spells for a small hp cost.
If you're going to focus on nukes, get Tsunami Pen - the strongest water nuke is compressed in Hydromancer Bloodmage, and the Pen provides a multiplicative damage boost to your water spells. Another option would be the revamped Kindred sword - it chargable autohit has some nice utility.
Keep Long Talon for wind, we don't really have any better options. Alternatively, you can use Carnagebringer to compress wind/dark and use a second Frostval Past weapon (their elevulns stack).
Use Mighty Blade of Frostval Past for ice. Its qc elevuln is an immeasurable boon to ice nukes like Horo Show.
Gloom Glaive compresses harm. Another option would be the recently revamped Troll Club. Its Berserk toggle gives the largest weapon-based damage bonus, but at the expense of your accuracy.
Your light weapon mostly depends on what light nuke you plan to use. If you hope to get another UR for Lumenomancer Bloodmage or farm tokens for WKZ, keep the Lumenomancer sword. Otherwise, grab Morningstar Cross. Being 100-proc, it's slightly subpar for regular armor attacks, but its skill has great synergy with Vamp's Evolved Form, allowing you to deal high light damage in darkness armor - not to mention the lifesteal it provides.
As above, the darkkness weapon depends on your planned nuke. If you want to use Angel of Souls, pick up the Reaper weapon from its set - the FSB gives you +30% damage. If you plan on nuking with D-Burst, grab Blackbones for a multiplicative damage boost to your darkness spells.
For your subrace, I would highly advise getting Vampire. Until you get Love Potion from Snugglefest, it's your only source of quickcast stuns.
Torontosaurus Rex has the strongest fire skill (outside of the UR Bloodzerker). Another option would be the Pyromancer Bloodmage (Caecus returns to the Void this Thursday).
Keep HBM for water.
The strongest wind nukes are premium, rare or UR, so I suggest just using your no-drop Vamp as a wind armor.
Horo Show Vigilante is an old standard armor, meaning it gets a really op elecomp bonus to the damage of its skill.
Eventually, you'll want to pick up Terra Bloodzerker for your earth nukes, but it's a UR and you don't have any to spare. I suggest just using Cthonian Count (vampire variant) as your earth armor for the time being.
Taladosian Robes have the strongest energy skill in the game.
As mentioned above, the strongest light armors are Lumenomancer Bloodmage (UR) and White Knight Z (token). Until you can afford one of those, I suggest using Blue Blood vampire variant.
If you want to use your last slot for utility (like Generalist Robes, Frostval Past or Geocastellum), you can keep Vamp no-drop as your darkness armor. Alternatively, the Angel of Souls in your storage has an hp-costing darkness skill with a very nice FSB bonus.
Fire doesn't really have anything outstanding, so you may as well keep Samukematsuri Buckler.
Celtic Wheel has an Int drive.
Accordion Shield in your storage is probably the best shield for vampires. Its control potency greatly increases your chances of Mesmerizing the monster.
There are quite a few good ice shields, but the one I would recommend is probably Pies. Its Cha drive would provide a small, but useful boost to your pets, as well as a slight damage boost via the booster guests.
Chieftain's Ironthorn has been updated. It no longer gives the op *1.5 damage boost, but it does function as a top-level earth shield and has a Str drive to increase your damage.
Scarab Shell has a toggle to lower monster MRM, which would increase the accuracy of all your (and your pets') attacks.
Lantern of Souls has a small chance to autoblock any hit and a nice FSB with AoS armor/weapon.
Call Dunamis, Call Thernda and Summon Poelala - those are your three URs. If you want a spare UR for something else, get Poelala and Essence of Carnage- it has a lower boost for Melee/Ranged attacks, but is completely f2p.
Most of your nukes would be compressed via armors, but you should probably pick up Warmaster's Burst for wind, and maybe keep D-Burst.
Archmage Research or Runic Binding can give you a source of harm damage if you couldn't fit one into your weapon slots.
Sizzler Splosion deals less damage than a standard earth spell, but autohits - which may come in useful against high MRM wind mobs.
Spectral Chains are quickcast and ice - which measn they have very good synergy with Frostval Past weapons.
Keep Purple Rain, of course.
Moonwalker's Grace is a qc Dex booster, great for PR loop.
The best pets for you wuld be Poe/Dunamis/Thernda boosters, but one is UR and the other two are premium. In their absence, here are pets with some useful utility:
Underwyrmling is the only pet in the game that can attack monster sp.
Kindred pet can gather charges for your Kindred sword.
Fujin pet inflicts DefLoss, increasing the accuracy of all your attacks.
Frozen Effigy can toggle to Freeze the monster, great synergy with any fire nukes.
When the Void rotation circles back to it in a few weeks, you'll want to pick up WoolZard, a pet that toggles between inflicting Sleep and EleVuln and can increase the infliction chances for an sp cost. Until then, the Morningstar pet toggles to inflict randomly DefLoss or EleVUln, increasing the accuracy or damage of your attacks.
PikaZard has a chance to paralyze the monster.
For light, your final goal would be Lepre-Chan, a booster pet that enhances all your light attacks, but it only comes back on Blarney. Until then just keep using the Fairy Godmother.
Model 294 toggles to inflict EleVuln, increasing the damage of all your darkness attacks.
Keep Essence Orb for sp and grab Rejuvenating Necklace for mp.
Shadowfeeder Pendant is one of the best meta enablers - by clicking on it, you can get qc celerity; great synergy with Purple Rain and any elecomped nukes.
Helm of Frostval Past in you storage can be clicked on for a bth boost, then switched to a damage misc for max benefits.
Keep Windter Crown for a universal damage boost. Alternatively, grab Grakma Warhorn. It has a togglable Berserk status which multiplicatively increases your damage by 21% w/o the ususal /2 penalty for spells - though it does come at the expense of accuracy.
Bell Shell heals a bit of your hp based on damage dealt. The heal is less than CoRS', but it also doesn't reduce your damage, making it an overall better choice for FO builds.
Morningstar Helm gives immunity to paralysis. If you want something a little more sp-efficient, Blood Ruby and Liquid Courage give resistances to paralysis and fear respectively.
Cracked Ornamentin your storage provides a universal bonus to status inflictions - nice for Mesmerize and Frostval Past's elevuln.
Hope the info's useful and don't hesitate to ask if you have any questions!