Jailoy's page

Magic item introduced in the campaign makes them immune to the sun, i have dispelled it before and used it against them. also, i could just kill them in there sleep, but thats not exactly fun for any one

Does it just protect them from the sun? Or does it remove their weakness entirely? If its the former, the sunburst spells should still work, its not killing them with regular sunlight, its divine enhanced rays that exploit their weakness if they have it. If the item removes the weakness, then it wont work. Depends on the exact effects of the item.

If you want to remove gear from as you said in the 1st post, there is alwasy disjunction and Anti-Magic Zone, they are high enough to encounter these.

Also, use mobile fights, neither seems like they have pounce or the like. Keep their opponents moving out of their range with diferent methods to limit their attacks.

Finally, there is always Tsunami to exploit the running water weakness unless they also got that covered.

There is probably a bunch of reasons why their bonuses shouldn't even be that high, but honestly the answer is much easier.

They are vampires, exploit their weakness for all its worth.

A couple of decently optimizied same level cleric and druids can make volley of sunbeams and sunbursts that they should have around 50% chance of failing. Get like 3 of them casting and its game over. Sunbeam or sunburst destroys vampires on a failed safe and deals shitloads of damage if not (they double dip the spell weakness being undead that get affected by bright light).

You can also lower the cleric/druids levels a bit (just need lvl 13 for sunbeam) so you can increase the amount of them while keeping the same CR, though honestly you should launch least CR 20 stuff at just the 2 of them considering their levels plus being vampire. Consider that an easy encounter for them should be CR 19, around CR 22 if you want it to be a boss fight (assuming its only them, more if they have extra friends).

I would say if the price was grand-fathered from 3.5, its probably because its was possible to craft it with a lower spell-level and/or caster level, resulting in the lower price.

If you are willing to use 3.5 material, Sacred Fist from Complete Divine is exactly what you are looking for.