[lua] [sql] Implement Dainslaif's add effect

[WinterSolstice8]

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What does this pull request do?

see title

Slashing resistance:
(these have massive dark res, so 1/2 resist as well.)

Slashing bonus damage:

No MDT/MDB resistance:

add effect proc rate ish

Steps to test these changes

hit stuff and proc dainslaif