THEMATICALLY I'd like something like a Rogue or Artificer archetype with:
Battle Engineer + Occult Slayer + Deepwood Stalker with Occult Slayer adjusted to work with ranged stuff a bit and Battle Engineer adjusted to work against undead instead of constructs, a bit less sturdy and more damage with Blessed Blades (and Bolts) in some shape or form as a class perk or something to steal from VKF t5; and if you have both the perk and vkf t5 you get some special bonuses. True mix & match to get the prime Van Helsing going or maybe use the oppourtunity to rework Mechanic to be more up to par with 2025 DDO. Or maybe they just need to go into VKF if they want that small blades fantasy.
Wracking Strike/Shot, but for undead. Instead of disabling constructs, disables undead. Caustic Shot that instead of aciding Constructs would inflict Light/Silver/Good damage or whatever on Undead, etc.
All about throwing daggers, crossbows, dualstyle crossbows, repeaters and daggers / kukris / shortswords / traps / contraptions. Interchangeably uses intelligence and dexterity.
The problem is that Occult Slayer is way too tank-leaning as a tree which is unfortunate for a build like this imo. I wish it was better offensively - and would probably need pretty considerable tweaks to work for a thing like this.
Practically speaking I think I want those things but I'd hate to see it end up as something that is spread too wide and in the end ends up as "meh". It's much harder to screw up a longsword/greatsword using vampire slayer along the lines of Vampire Hunter D -esque idea that Sophie mentioned that hits undead hard and moves around well while "marking" and stalking/hunting properties to singlemindedly destroy undead / evil enemies.