Warlocks got very little from the new imbue mechanics: Spiritual Retribution is a d6 light imbue; Celestial Spirit form (Enlightened Spirit core 18) adds +3 Imbue dice. If you're playing, say, a
Vistani `lock you probably gained a little bit more melee DPS, but not exactly a build-shaking improvement.
Bard has two imbue options: Resonant Arms (d6 Sonic while Swashbuckling) and Iced Edges (d6 Cold). Warchanter cores grant a max of +5 Imbue dice (including capstone); +1 Imbue die from Music Box (Swashbuckling with a Rune Arm).
Artificer: Thundershock is a d6 Electric Imbue; +4 Imbue dice with Runearm equipped from Battle Engineer (Agility Engine + Unlock Potential); Greater Elemental Weapons (level 4 Arty spell) is +2 Imbue dice.
Of the classes mentioned, I think your best option is pairing Inquisitive with Artificer like
this build. If you don't need the benefits of barb splash (Blood Strength, extra runspeed, etc.), then you could splash rogue 2 instead. Imbue dice from class / Enhancement bonuses should cap out at +15 dice.
- +7 dice from Inquisitive (41 APs)
- +3 dice from Agility Engine (23 APs)
- +3 dice from Toxin Affinity (8 APs)
- +2 dice from Greater Elemental Weapons
Leaving enough APs to grab Know the Angles.
If you're not wedded to Artificer, Alchemist 18 / rogue 2 can pick up a
few more Imbue dice via Vile Chemist instead.