Fantastic universe, but not necessarily magic involved in the process. You face a guy who has a shield (tower shield ofor not). You do not have a shield, but you are a better swordsman. How do you win?
According to Dark souls, your best option is to kick the shield, but realistically speaking it is hard to think of better ways to leave yourself exposed to a counter attack. Other video games taught us that waiting for your opponent to attack and leave an opening is the best way, but if your opponent is worth his salt he will likely block most of his openings (as shown in this video).
So my question is: how can a skilled fighter (with swords, maces, etc) deal efficiently with shield users, other than tiring him or reducing it to splinters?
FYI: Yes, I do consider a shield a weapon as much as a mean of protection.
Post-answer edit: TheDyingLight answer was the most complete of all (mainly because my open question not specifying the weapons/armors involved), but please check the rest of the answers too. Each one adds a new detail, a new point of view on the matter that you cannot ignore and certainly I will not. As my first post on this site, I sincerely thank each and every one of you.