In order to obtain the Crossbow of Light, you’ll need 4 pieces to complete the symbol. The Crossbow of Light runes can be found at the below locations!
1. Complete The Tower Tour side quest!
2. Zallata in Solino Valley
This rune can be found by completing the puzzle at Zallata in Solino Valley, which can be found along the beach northeast of the Sun Umbrella seller. Play the horn on the guardian symbol to enter the tower. Once inside, descend down the ladder. Place the two pumpkins on the moving platform in the middle then get on to be ferried to the other side. Retrieve the pumpkin there then get back onto the moving platform. You’ll have to be quick about it but you’ll need to throw all 3 pumpkins at the eyes on the columns.
Once all eyes have been momentarily shut, the chest containing the Crossbow of Light rune will appear.
3. Abbascio in Sinaro Meadow
This rune can be found at Abbascio on a high hill in Sinaro Meadow. To reach it, you’ll need to climb up the hills at the bottom of the area and make your way to the eastern side using a log to cross to the hill containing the tower. Once inside, use the blocks to stop the fast spinning things so you can carry the owls to the circular spaces on the floor.
When all the owls have been put on the circular spaces around the main circular space, the chest containing a Crossbow of Light rune will drop!