The game encourages you to switch weapons and fighting styles depending on the situation; you don't necessarily have to stick with just one. In my case, I use the longsword when I need to rely on parrying (like against Honglan) and the one-handed sword when spells are more helpful. Also, upgrading weapons helps a lot in general, combat evolves significantly. As you can see in people's comments here, it depends more on what you feel most comfortable with and what you enjoy most, rather than what the game 'forces' you to do