Part 3/7:
The phial served multiple purposes beyond merely casting light. It was specifically crafted to shine even brighter when encircled by darkness. The unique quality of the light contained within was a powerful deterrent against dark creatures, enabling Frodo to repel Shelob during their encounter. This encounter was pivotal; without the phial, their fate would likely have been sealed by the monstrous spider.
As Frodo faced the perils at the entrance of Shelob's lair, the phial provided not only light but also clarity of mind. In the books, Frodo, overwhelmed by the ring's heavy influence, feels a sense of relief and hope upon touching the phial, which temporarily banished the malign thoughts of the ring.