This WeakAura analyzes the enemy setup on arena match and performs the automatic weapon swap, depending on their possibilities to Disarm you.
Ideally, you want a secondary PvP set with different melee weapons, enchanted with Titanium Weapon Chain.
Pre-setting your sets via standard Equipment Manager (ESC -> Settings -> Features -> "Use Equipment Manager") is a mandatory step. You need to do this via Custom Options of this WA.
PLEASE NOTE: set IDs start with 0 in Equipment Manager's selection window.