The Skill Bar & Weapon Swapping - Each class has 10 skills, now you must be thinking “WTF ONLY 10?” Well it’s not as simple as “only 10”. Every class can do real time weapon switching (thanks PS3!) in combat, this switches your skills based on the weapon you have equipped.
All but two classes can swap between 2 weapons at a time (read below for the exceptions).
In combat you’re going to be expected to swap your weapon sets to maximize your effectiveness. A Warrior can swap from a Rifle inflicting conditions on a single target starting out and then into a 2h Hammer for AoE damage when his foes close in. You could use a 1h Axe & Shield for quick adrenalin building and high damage attacks, drop back out of the way and switch to Longbow for massive fire AoE damage.
The weapon type you have equipped defines the skills you have in your first 5 slots. Say you're a Warrior and you're using a 1h sword in your main hand and a shield in your off-hand, your first 3 skills will be sword skills while your last 2 will be shield skills. This is a bit different for the Thief though, say you're using a pistol & dagger, the first two will be pistol skills, the third will be a combination of the two weapons and the final two will be dagger skills. If you're using a 2h weapon all 5 skills will be from that weapon.
The Elementalist can only use one weapon at a time and can't swap due to the attunement mechanic, but they end up having access to more skills to make up for the lack of weapon swapping (20). The Engineer also is unable to weapon swap, but instead they can swap out backpack kits, weapon kits, and turrets.
The other 5 skills on the bar are all changeable to whatever you wish; this isn’t locked down at all.
6 - This is always your heal button, you can change this to whatever heal spell you currently have access to.
7-9 - Are your utility skills you can choose from, for the Elementalist this consists of things like Conjuration, ethereal Forms, Glyphs that modify your abilities, and Signets which gives you a passive and active effect once you use it.
0 - On your skill bar is always your Elite skill, for now the only one we’ve seen of the Elementalist is the Form based ability ‘Torando’ which turns you into a tornado that you can move around dealing massive damage and launching enemies into the air.
So for a single weapon build of an Elementalist you’d generally have 44 spells to use. In total with all of the weapons accounted for, you could be managing 139 unique spells based on your second hotbar setup. Ultimately this is something you’ll need to learn because you will be expected to fill any role at any time.