Complex sentence: Daeron of Doriath independently of Rúmil and Fëanor had invented the Cirth runes, but these were only used for inscriptions, and otherwise replaced by the Tengwar, except among the Dwarves.
Split into simpler sentences: Daeron of Doriath, independently of Rúmil and Fëanor, had invented the Cirth runes. These were only used for inscriptions, and otherwise replaced by the Tengwar, except among the Dwarves.