Your idea of basing the character around the longsword attack suggests an idea to me: what about a dex-focused elf with weapon finesse (longsword)? You could build a feat set based around the dodge and expertise feats with an emphasis on the character's movability.
There are many possible class directions -- ranger, rogue, fighter, bard, barbarian but what I would personally favour is either a fighter/rogue or a fighter/bard.
There are many possible class directions -- ranger, rogue, fighter, bard, barbarian but what I would personally favour is either a fighter/rogue or a fighter/bard.