Well... what are you going to use the PLD for if not
for tanking endgame events? If you want to DD you'll be better off using SAM in every case I can think of. For example I'm not sure why you would want to merit on PLD rather than SAM.
If you want to tank, then you'll want to work on getting a good PLD/NIN haste + enmity set up. There are various gear guides that list a lot of it like ScarShiva's PLD/NIN tanking guide (http://ffxi.allakhazam.com/db/jobs.html?fjob=5;mid=118238578826245816;num=77;page=1)
and NCcoda's equipment guide - see the section on endgame tanking about 1/3 of the way down (http://ffxi.allakhazam.com/db/jobs.html?fjob=5;mid=117494950071983378;num=36;page=1).
In short, basically anything that has loads of enmity and/or haste is useful, and shield skill is another great stat to invest in for when your shadows go down. Homam+swift belt with Macahuitl+1 and Wivre shield is a good starting point.
The thing is that most of the gear you would use is rare ex. You didn't say what r/ex stuff he has so I'm not sure what slots you still need to fill. You can probably figure it out if you check out the guides.