It is not enough to simply know the name of one's Zanpakuto. If a wielder were to lend its power to its Zanpakuto then the weapon would become stronger. To fully use a Zanpakuto's power, a wielder must get to know its Zanpakuto's spirit.
Jinzen (Blade Zen): This method is the only way to carry on a proper conversation with one's Zanpakuto. One places their sword over their lap and takes a meditative pose and then forces their mind to become one with the Zanpakuto.
In this form, one can call out the true form of the powers of their Zanpakuto. This form is something that Soul Society has worked out over the thousands of years since its formation. It is entirely about speaking with one's sword. This advanced form of training is far different from attaining abilities by force. In this form it is about entering a state of calm to enter the inner world of the Zanpakuto and engage them there. In this state a wielder will have to fight their Zanpakuto spirit in order to attain access to new abilities, the Zanpakuto spirit does not want to teach these moves and engage the wielder in a battle the likes of which has never taken place before.
In this meditative state, one is so deeply entranced that even sustained wounds are ignored. Any form of injury sustained in the inner world while in this meditative state is reflective in the real world.
Mood & Communication
As stated, a Zanpakuto is a being unto itself and tends to be highly temperamental. Its mood is determined by how it is treated by its Shinigami as well as its overall personality. This allows a Shinigami to partially determine whether it will achieve its true power or not. For example, Yumichika Ayasegawa normally releases his Zanpakuto with the name Fuji Kujaku (Wisteria Peacock), even though its true name is Ruri'iro Kujaku (Azure Peacock), knowing that its favorite color is azure and that its least favorite is wisteria purple. He does this so that its true power is not seen. Since his Zanpakuto hates the nickname, it becomes moody and only releases a fraction of its power. This allows him to pass off his Zanpakuto as a simple melee-type rather than what it truly is, a Kido-type, something that is unacceptable in the 11th Division due to an unspoken rule that all Zanpakuto in the 11th Division must be melee-types. Only when its true name is uttered does it achieve full potential.
Another major exception to just about all of the aforementioned rules, 11th Division Captain Kenpachi Zaraki, somehow failed to learn his sword's name. He ignored its living embodiment and preferred to use it simply as a tool, relying only on his own power. He never developed the control to seal his power, and thus also breaks the rule/tradition of keeping a Zanpakuto sword in a sealed form--his sword is always in its true form. Zaraki's immense personal strength not only made it possible for him to break these rules, but also to rise to the rank of captain. However, his neglect wasn't exactly good for the weapon, causing immense pain to its embodiment and damage to the sword itself.
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