Guild Wars 2

When you have to chose to carry only one Warhorn on your Tempest as an off-hand weapon (so we are talking S/WH or D/WH), which prefix attribute stat works best with the skills on the Warhorn and the associated skills on it?

Heat Sync – no damage component; might boons
Wildfire – base damage component, burning condition

Tidal Surge – base damage component; long regeneration boon
Water Globe – healing component

Cyclone – base damage component; long swiftness boon
Lightning Orb – base damage component; vulnerability duration component

Sand Squall – no damage component; boon component
Dust Storm – base damage component; small condi duration component

I can currently see do gear set-up in game that helps us with boons (Giver’s), because our abilities to created and handle boons comes from our traits / trait lines.
With no big damage skills on the Warhorn (e.g. in comparison to Churning Earth or RTL), should the WH carry stats that augment the main hand weapon?

I am currently thinking that you should either put the same stats on it than you current off hand (Focus or Dagger) or just chose Celestial for it, because that helps you in general with your stats.

What are your thoughts on it? Am I missing something or got something wrong?