The quick answer

A skill bar, a skill specialization tree and your class passive trees are different systems. An unlocked skill can go on the bar; specializing it unlocks its own tree progression.

Unlock and specialize

  1. Open the skill window with S by default and check the skill’s unlock conditions. Skills may require character levels, passive investment or a particular mastery. A planner can display a skill before your character can use it.
  2. Specialization slots unlock as your character progresses, up to five. Select an unlocked skill and gain experience to earn its tree points. The base skill level cap is 20; equipment can add extra skill levels.
  3. To replace a specialization, use Respec at the top right of its tree. The replacement begins at your current Minimum Skill Level and may receive catch-up experience. Read the window and XP bar for your character’s actual state.

After a respec

Regain skill levels in content you can clear reliably before returning to higher difficulty. Being able to change a skill does not mean its old level transfers without loss.

Passive-tree respec uses the Chronomancer and gold; it is not the same as moving skill experience between specializations. A successful skill change shows the new specialization, allocatable points and a progressing XP bar.