PLD is probably the easiest class to play, some will say its boring, I enjoy it. As long as you are using all your abilities the healer should have no issues keeping you up. First thing you may want to do is start the relic ques to get a better sword and shield and then the first upgrade is really easy. There is an NPC in Vesper Bay in West Thanalan to talk to to initiate the quest The Weaponsmith of Legend. Get that rolling and get the Curtana and Shield, you will then be able to upgrade it. Unless you have the money you could buy a weapon off the market board.

The thing with the Relic is it is very long upgrade process to 135 only to have it replaced in the xpac. If you plan on getting the xpac I probably wouldn't bother upgrading it past the Atma stage. Just grind out the rest of the Main Story and get into the xpac. If you don't plan on getting the expac then I would take the upgrade all the way to the end. Though you can get a comparable weapon drop from the high end raid dungeons, but that could be a whole different animal.

There are alot of ifs ands or buts to the game and for a new player you need to decide if you are going for the xpac or not and then what to upgrade.