Viewing the choice of subjob in terms of DD potential is irrelevant to this thread. People saying "/war only" are quite outdated or just not intelligent. sure, nin/war is the best option for DD and tanking, but honestly, if you want to DD or tank then dont use nin. sam mnk drk war are all better jobs at both damage and several jobs can tank better for 90% of the content out there. who has ever seen a nin tank or nin DD in voidwatch? nin will die from aoe as fast as any other job, and you'll never see a nin outparse the 2hander jobs. nins are basically a mage in VW, and that should tell you everything about nin/war combo in today's FFXI.

I personally use nin/dnc as much as anything. nin/dnc is what you would use in dynamis farming, and its probably the best soloing combo. violent flourish is also a very useful stun capability that i make use of in all sorts of fights.

other fun subs would be /sch, /rdm or /blu. sch sj is always interesting because you can use arts to bump up your magic skills, allowing for use of sleep etc. nevertheless, all these mage subs are just fun and not useful in any group events.