Soul Resonance is performed when the Meister's Soul Wavelength is sent into their Weapon, which then amplifies it and sends it back to the Meister. This process is done repeatedly. In turn, performing this generates a strong Wavelength which can enable a powerful technique to be performed. This relationship has been compared to the usage of an electric guitar and an AMP by Death, who explains that while the sound (Soul Wavelength) that comes from an electric guitar (Meister) by itself is rather faint, it gains a lot of power when connected to the AMP (Weapon).
Multiple Wavelength Matching
It is a known fact that it is usually extremely difficult for an individual Meister to match up with more then one Weapon's Soul Wavelength, requiring talented Meister for such a capability. Those capable of doing so are known as Utility Meisters. It's also possible for multiple Meisters (up to even 3) to even match one Weapon at a time, although such a dynamic is rare.
Team Resonance (チームでの魂の共鳴, Chīmu de no Tamashī no Kyōmei), also known as Chain Resonance (共鳴連鎖, Kyōmei Rensa) and Resonance Chain, is a kind of resonance that involves a team of Meisters matching their wavelengths with one another in order to empower each other. It is extremely difficult to maintain, unless all the team members can easily keep their souls on a balanced level. There is no set number of Meisters required to perform a Chain Resonance, but it is more powerful yet more difficult in a larger team.
Bonds are methods of resonating exclusive to family members such as parents or siblings. No matter the circumstances, it seems that a family member can always wield another should one be a Meister and another a Weapon. Even Soul Resonance attacks are possible. However, despite that, resonance between family members is not as strong due to a similarity in wavelength.
Other forms of Resonance
Screech Resonance (悲鳴共鳴, Himei Kyōmei) is the form of resonance that Crona and Ragnarok use. When initiating the resonance, the mouth that appears on Ragnarok (as a weapon) opens wide and screams out a loud sound wave. This sound wave makes Ragnarok vibrate like an electric saw, increasing his cutting power, and can also radiate through the air causing internal damage to an opponent and even other Weapons. This is shown when Soul feels pain and is injured even in weapon form just from being in contact with Ragnarok. Besides the piercing sound wave, this resonance function the same as a normal Soul Resonance.
An Engineered bond is a bond in which a Weapon and Meister are permanently bonded into each other artificially. Crona and Ragnarok are the only two individuals in an engineered bond within the series.