Re: Dweomerkeeper build help
If you're able to use a FR-specific prestige class, can you use FR-specific feats as well? If so, get Magical Training (PGtF) to meet the arcane casting prerequisite of Dweomerkeeper, and get Servant of the Fallen (LEoF) to get around the current and any future lack of deities. Also be sure to pick up Initiate of Mystra (PGtF) at some point if possible, though it's typically delayed until around 9th level.
If you can use flaws, use one of the elf races, and later on you can (Su) Dark Chaos Shuffle your four racial marital weapon proficiency feats into four Extra Turning feats to power DMM: Persist. If you're doing this, you should also spend some starting gold on one or more bonus feats from visiting the special locations detailed in Complete Scoundrel, which can also be Dark Chaos Shuffled to something more useful.