A triple air alchemical weapon gets slightly more DPS than a Lit 2 plus Stunning +10, and can break DR even better depending on what you slot its red augment crystal with.
Specifically, with Triple Air you get a +6 weapon with greensteel dice (e.g. 1d8 khopesh -> 1d10), plus your choice of metal type (silver, cold iron, flametouched iron, etc.), plus Shocking Burst, Electrifying Blast (AoE 15d6 electric damage on a vorpal roll), Stunning +10, Insight AC +4, Ex Dex +2, Lightning Strike, Doublestrike +6%, & a Red Augment Slot.
The combinations can be found
here.
So you could, for example, have a Flametouched Iron (to break good DR) Triple Air weapon with a Red Augment Crystal of Metallic Edges plus Deadly Weapons. This does slightly more trash DPS than a Lit 2 in most cases, is metalline, breaks good DR, and has extra base damage due to deadly weapons.
If you can't maintain the metalline augment crystal, then you could just slot silver.