If the Wizard only has to see something once to perfectly duplicate it (even without studying it carefully), here are a few things that work.
- A Map
- A Secret letter (he can look at it once, destroy the original and then when he gets to the location to give it, use Minor Conjuration to reproduce it, no chance of it getting stolen)
- A Key (Get out of Jail, into homes)
- A Small Boat (Ok, more like a plank of light wood to hold onto in the water but still)
- A Sled!
- Food/water ( but he gets hungry again an hour later )
- Most Artisan Tools
- Glowing Cloths (he can be a fashion thief!)
Depending on the definition of 'takes damage' then a weapon or even armor (since they never 'take damage' when you are using them in combat, DM call though)
It never says anything about the object being a perfect replica, and it's doubtful it could make a map or document with words you haven't read.
"Sometimes, we’re heroes. Sometimes, we shoot other people right in the face for money."