well summoner is something like a magican so you only use spells but never directly hit with your weapon so only your magical wand will increase your dmg output directly the weapon like a sword for example only gives your the stats on it like +20 proficiency or whatever it has but the general weapon dps itself doesnt matter for you

so its up to you to choose 1hand + offhand,slow 2 hand or fast 2 hand as it makes no diffrence for your dps
only keep in mind if you for example use dagger + offhand then you have to collect (find) 2 items instead of 1