This would be Merlin, who defeated the druids of Ireland in spell battle and then flew back over the Irish Sea riding Stonehenge. Who created another stone circle by turning a group of Saxon magicians who attacked him into stones. Merlin had significant limits, far more than a D&D magic-user, but he's not just a sage by any means.
It really depends on which legend you are reading. Mallory romanticized a lot of earlier versions including adding the whole Lancelot, Gwen and Arthur triangle as being one of the downfalls of Camelot.
In earlier versions and later versions after Mallory, Merlin is more of a sage. It was Arthur who untied the warring kingdoms under one king. If Merlin was so uber powerful he and Arthur would not have needed an army of knights to force the capitulation of the other kings.
And it is this version Merlin I was talking about when describing wizards. The things Merlin did in the uber magic version was done without a spellbound so that would make either a powerful sorcerer with some levels in druid.