Don't tell a berserker to go to anger management.
The berserker is a powerful melee damage class that wears heavy armor. Characters with high strength and stamina do best as berserkers, as those are their primary statistics. The primary role of this class is to put in serious hurt on your targets, either dual wielding, using two handers or standing behind a shield. The berserker can also act as a strong tank, with very good threat generation and a high degree of mitigation. Their ability to switch between offensive and defensive stance allows them a high degree of flexibility on the battlefield. Don't be fooled by the name - they can be just as effective tanks as any other class, if not one of the best due to their wide variety of threat-gaining abilities.
If you're getting into the berserker class, you should expect to tank much of the time. It's a bit more involved than simply doing damage, but you'll often be the best character for the job. As a tank, you'll need to be comfortable in a leadership position. You'll need to act quickly, know how to pull, and maintain threat on a variety of enemies. Luckily, the berserker has many area of effect skills that they can use to build threat like Whirl and Growl, and powerful retaliatory skills like Intimidating Defense. Just like most classes in EQ2, Berserkers get a new skill at least every level, and it takes a solid player to make the best use out of all of them depending on the situation at hand.
It's easy for berserkers to hold threat on a single target, but it gets trickier when you have multiples. Use all of the abilities at your disposal and get your group to use an assist macro to bring down each of your enemies one by one to make things easier for you. Using a stance like Hunker, which increases your mitgation while decreasing your movement speed, is an excellent skill to use when you and your party have a good handle on threat. Keep the right war cries going for your party as well, depending on the needs at hand and your class composition. The Intercept and Reckless Aid lines are excellent protections if one of your group members pulls agro - have those ready to go if you see one particular character continually pull monsters off of you.
When the berseker isn't tanking, you're an excellent area of effect damage dealer with a great deal of survivability. It's nice to have an additional tank with the group as well in case things get out of control.