Though the original intention for the Lightwell was unknown, it and the surrounding city of Juruna is a major location for Nokana metal manufacturing as well as magic studies. All Mithril ore is sent to Juruna to be purified into a metal state, and typically any other metal is sent here to be purified as well. The Lightwell provides the source for the concentrated light needed for Lightblasting and other clean ways of metal smelting.
Mages come to Juruna to study the Lightwell, particularly because the practice of light magic is extremely hard to master. Having a pure form already in existence to work with helps them, since concentrating light yourself is only a master technique... And without the Lightwell no one could learn light magic.
The components to the Lightwell are relatively simple, however they materials used are extremely rare across the continent. The first and most prominent of the components is a giant Deonite Lens. The lens is used to focus the light from the sun into a large, constant beam. The beam is then sent down to a large Aureus Splitting orb, which is multi-faced to split the concentrated beam of light into a mist-like, slow-moving current of light. This is the light in its purest form. Currently Deonite is deep into the ground and sparse across the continent, and Aureus has only been found in two places on the planet and in few Lyrian ruins. This makes replication of the well near to impossible.