lol i first posted about socketables, not the sockets themselves.

afaik you can enchant armor, weapons and shields to get more sockets in them. i forgot which enchanter does that and which town / dungeon he first appears in

Jurick the Socketer can add sockets to things. He can definitely do weapons. Not sure about shields, but I suspect so. I've seen him as early as Act 2.

You can also go to the Transmuter in any town except the first, and he'll add at least one socket to an item. It'll require two gems of the same item level or higher. If you get lucky, you'll get two sockets out of that, but it's pretty rare.

Jurick just wants cash.


https://torchlight.fandom.com/wiki/Enchanting_(T2)

Jurick can add sockets to any equipment with less than two sockets already. He is most commonly found in large cave maps.

Level 99 Netherrealm Weapons (and Shield) have 4 native sockets each.
Asphyx 2-piece Set Helm and Glove also offer 5 native sockets each.
Some (blue) Rare-Tier weapons will also carry 3 or even 4 sockets randomly.
Some 2-handed Unique weapons also carry 3 or 4 sockets.

Randomly encountering Jurick in a map (2-sockets-total limit and the only Socket Enchanter) has competition for player builds because of these other options.