Sykar
Arcane
People have given slightly incorrect answers -- Solael's Witchfire adds some flat damage to any physical attack, which some spells do fall under such as Phantasmal Blades (you'll want to get to and max out Second Rite for the% bonus as well). Also Consecrated Blade changes it to require a melee weapon only, no guns. Unless they changed it in a hotfix or something.
In terms of high end equipment, there's lvl 40-50 uniques for pretty much every slot for a vit damage build, and you have the choice of going dual-wield (2 Lifebinders), two-handed (Scythe of Tenebris, your best overall option if you roll a good one and don't mind using chaos damage), or 1-handed and the grimoire of Og'Napesh for a pet and decent vit damage bonuses. Sadly it takes a lot of grinding through the end of act 3 to get all the 50 uniques, or you might luck out and roll a good rare. I'd recommend Doom Bolt over Sigil of Consumption as it's much better v. bosses.
And Veteran mode can be a bit challenging when you fight the very first mini boss, but after that as long as you've made a slightly competent character it's not so bad. Normal is way too easy for the most part.
So you are saying it does not work on spells like Doombolt at all?