I presume you're talking about the Warrior Class? Warriors can specialize in 2-H or using Shield making them having to choose between the two. In contrast, Clerics can switch between weapon types rather effortlessly as their skills apply to all weapon types.
The 2-H vs 1-H with a Shield debate is a deep one. Neither has a clear lead. And that's how it should be if everything is in balance. So it boils down to playing style.
2-H Warriors, esp those that are combat focused, will have the easiest type with fighting, but might miss out on dialogue and quest options. Some of that can be avoided with having Adaon in your party or having a few trait points invested in Mental Traits. Dungeon runs tend to be fast and furious. Charge + Whirlwind is a deadly combo for those that learn the timing. Maxed out 2-H expert does wonderful with damage and stun.
1-H Warriors, esp with Infantry Training and Duel, can be defensive tanks with impressive damage output. The extra elemental resistance from having a shield plus a non-whispering necklace makes a difference, too.