Couple QuestionsFollow

The Shadowknight is a tank class. The low damage assertion though, is false. While they aren't a top tier DPS class, they are arguably the highest DPS plate tank depending on the sampling time and situation. We deal out very nice damage and bring a lot to the table. Depending on group make-up a Shadowknight can kit themselves for tanking or DPS. The damage output of a good Shadowknight is more than respectable. It sounds like an SK is what you are looking for in ability. High damage plate fighter. Life taps. Stat taps. Disease based direct damage and DoTs. Evil bastards.

Will you be forced to tank? Sometimes. You may join a group and there is no other tank besides you, and you will naturally be asked to function in that role. There are other times where you will join a group and there will be a better tank available for the situation and you'll be able to sit back in a DPS/utility role. If you like to solo from time to time, there probably isn't a more effective plate-wearing solo'er.

It sounds like a Shadowknight is what you are looking for. Whoever told you that they were low damage were mistaken. The only caveat you may want to be aware of is that it /is/ a tanking class and you /will/ be expected to tank from time to time. If this is unacceptable to you, then you need to rethink your position and maybe roll out a pure DPS class like an Assassin or a heavy damage mage.