What is the point of this?

You are guaranteed to have one card of your favorite type in your opening hand. I usually choose weapon.

Same here. As Lem only has one weapon in his deck, getting that weapon guaranteed at the start is great.

Same here, even when I build him as a caster primarily, it's good to have that weapon as a backup, as he doesn't have that many spells and a few are usually taken up by utility.

I choose weapon as well; starting out with the deathbane crossbow +1 is a big help.

This class feature helps make Lem a man of ultimate flexibility. That being said, always pick weapon until you have a reason not to. Once he gets Loot cards you can start guaranteeing them in your opening hand. #ProTips

What people who do not play the card game may not realize is that every character, besides Lem, has a favored card type, and is guaranteed to have a card of that type in their opening hand.  This  is why certain martial characters like Valeros and Harsk always start with a weapon in hand, while Seelah, Merisiel and Kyra can struggle along looking for a weapon at the start of the game.