Actually, I have 2 books that I've been trying to remember for months now, and drawing a complete blank.

The first one is set in Scotland I believe, and the main character's name, if I'm not mistaken, is Robert something, and he and a small group of people protect the world from harmful magic. He uses several forms of magic, though I think he's good at hypnotism, and he has a police officer Freemason friend who helps him, and is teaching a painter who is able to paint the future or past of his subjects. I think one of the books has "Dagger" in the title. Most of the books have a celtic theme to them, with one involving a scottish castle with a ghost, and fairies, and another involding druidic sacrifices.

The other series is set on this island kindgom without magic, which gets invaded by a people who all have different magics, including shape shifting and creating golems. The holy water from the church on this island is able to kill the magic users. In one of the later books, I think, the king of the invading people has been killed, but is in the mind of his granddaugher who is the daughter of the king of the island and the invading king's magical daughter. The girl is able to shift to many forms, instead of just one the way most of the other shifters do. Also her brother was taken by the king and swapped with a golem.

I'm sorry if my descriptions are a little rambling, but I tried to remember as much as I could about both series. I would really love it if someone could help me with these, it's been driving me crazy for months.