I have also posted the question on a
bioware forum and they tell me that the last in, last out method used for equipment can be overridden with a script. I have asked the bioware user to share his script for a container which is used exclusively to equip arrows, but I am thinking it might be easier to script an "anti quiver" from which projectiles will never be equipped.
This would be particularly useful for the Eastertide arrows.
All hail the great and powerful Ziroc!