It would make little sense if only seers could make wands, what with the rarity of seers, them not being known of even by Mr. Verres, and wands apparently being standard issue for paranormal investigators.
As Pandora points out, however, it might well be that seers are responsible for others being able to make wands, even if they're long forgotten and haven't been given credit for it. If nothing else, the tools (possibly wand-making-wands), likely originated with them.
The potential for seers actively making wands without anyone realizing they're a specific type of wizard, or even wizards at all, is also an easy oversight to make given EGS's magic system:
"You can see magic? That must reflect your insightful personality."
"Oh, you can create wands? You've always being the sort to build things."
"That is an impressive resistance to magic! Well, it's to be expected, what with your bloodline."
Etc, so on, and so forth.