My main (and only, since you can play any class with the same character) in FFXIV is an Archer. (Or "ARC," as they like to abbreviate class names to 3 letters for some reason – I still have trouble translating those – ARC looks like Archive to me – why is it hard to add three more letters to make "ARCHER?") Archer is a straight-forward, low-stress ranged DPS class that’s fun to play.
When you reach level 30 in Archer and level 15 in Pugilist (or PUG, which obviously stands for pick-up game), you can specialize in the "job" of a Bard (or BRD, which looks more like Beard to me). You are now asking how combining a bow-wielding archer with a fist-punching monk-ish class turns you into a music-playing bard, aren’t you? I don’t know the answer to that. There’s some FF lore to explain it, but the bottom line is that it just does. It’s one of life’s great mysteries.
You "enable" your BRD by equipping a job stone thingy. The BRD is about 99% the same as an ARC. At first, you only get one new ability, which is a buff that uses your mana to restore the rest of the party’s mana. That’s a reasonably handy spell in a group, as I would imagine it to be quite helpful to a healer.
Unfortunately the Beard’s mana buff ability comes with a pretty steep price. The first is that while the Beard’s mana buff is up, the Beard’s damage is reduced by a whopping 20%. Not cool when you’re supposed to be doing DPS.
The other big problem with the Beard is that you can only pull in alternate abilities from the Pugilist and Lancer classes. Those skills are … what’s the word I’m looking for here .. TOTALLY USELESS. Yes, that’s the one. (Well, mostly.)
However, I quite often need (or want) the ability to throw out a heal, which I can only do if I remain an Archive. When I’m soloing, I sometimes need to heal myself. Now that I have a chocobo companion, I sometimes need to heal him. Sometimes when I’m in a FATE group I might see a tank about to die and I might want to heal him up. My heals are pretty terrible compared to those of a dedicated Conjurer (CNJ, or kunge), of course, but they are better than nothing.
So I guess my point is that the Beard doesn’t feel terribly useful in the overall scheme of things. I can see where the mana boost would be helpful to a party, but is it enough to compensate for the DPS loss and the loss of off-healing capability? I’m not so sure. If Beard is supposed to make you into a support class, why rob you of the ability to off-heal?