The Guild Wars 2 skill bar has changed from the one we know and love in Guild Wars. Isaiah Cartwright, a games designer for Guild Wars 2, gave some insights during an interview at Gamescom 2010.
There are ten skill slots, 5 on the left, and 5 on the right. In the middle is a round, red ball depicting how much health your character has left. Above the skills on the right is a bar indicating energy. On the left hand side, all characters have a bar or some other link to a professional ability. This is almost certainly a nod towards the primary attributes of the original Guild Wars professions.
The professional abilities are Adrenaline for the Warrior, Attunements for the Elementalist, and Death Shroud for the Necromancer. The Ranger has a pet, and this takes the place of the professional ability. As you play, and fight, the bars fill up, giving you access to special profession-related attacks. These attacks may add power to your existing skills, or they may bring in a new set of skills to use. The elementalist, for example, can change from fire to water skill simply by changing attunement.
The pet has its own skill bar, and the Ranger can choose which skills to equip on the pet. Different pets have different skills. Once the skills are equipped, the pet attacks automatically using those skills.
The skills on the left hand side are linked to the weapon your character is using. You may change weapons while fighting, which means that you effectively change the skills available to you. So if you are a necromancer, you can change from blood to curses skills simply by equipping a curses-based staff. If you equip a hammer, you automatically get hammer skills loaded into your skill bar.So, if you're playing and a new weapon drops for you, you can try it out immediately without worrying that you have the wrong build for it.
The skills on the right hand side are for skills of your choosing. The first slot is for the healing skill of your choice; the other slots are for elite and what are broadly termed "utility" skills. Elite skills become available in a number of ways, including skill trainers, quest rewards, and drops. You will be able to create builds on the right hand side but, as yet, there is no mechanism for saving builds to a template. It is unlikely that the first release of the game will have templates, due to the amount of work involved in setting these up. The game designers do want templates, though, so they will probably be released in a game update.
There are skills that are combination skills, but they use only one slot. When you use the first part of the combo, the next part loads into the slot automatically.
The demo game had only limited options for right hand skills for the level 47 Charr; in the final release you will have a huge variety to choose from. You may equip skills in the right hand bar any time you not actually fighting. If you have time between defeating one foe and attacking the next, you will be able to change to a more suitable skill.
As you play GW2, your character will acquire Traits; these will modify your skills and allow you build a uniquely customised skillset.
When you lose all your health, your skill bar disappears! Instead, you get a little mini skillbar with four skills you can spam to try and recover. As soon as you kill a foe, you get all your skills back. This sounded quite terrible in the description that ArenaNet put up when they announced it; in actual play it is marvellously exciting! Unlike suddenly discovering your character can't do anything because it has died, you suddenly get this new set of skills popping up - a warning you need to do something fast!
If you are defeated anyway, fellow players can revive you. This seems to require no special resurrection skill. Few people in the demo games ran to revive other players; they were probably trying to squeeze the most gameplay as possible into the demo play time of 40 minutes. If no one revives you, you can choose which point on the map to revive at.
A starter character has two weapon skills and a healing skill. As you level up, you unlock additional skill slots. A small book appears in the skill slot to alert you. You cannot buy skills for a higher level than you have unlocked.
All in all, the new skill bar looks to be an exciting evolution. The feel of play is much the same as in the original Guild Wars, but there is plenty of scope to create truly unique builds.