I want to understand the effect of tattoos and piercing on various parts of body, such as a hand, on a spiritual, psychological level? Do some type of tattoos increase the spiritual energy, or does it act as a barrier?
I do not know of a place where your question about tattoos or piercing is addressed by any of our line of Masters or Swami Kriyananda. However, we can infer a few things from their related teachings.
The Great Ones do teach that the human body is sacred and is wonderfully complex on a physical level, but even more so within our energy or astral bodies, which we all possess, too. The ways energy (prana) flows throughout the body certainly might be influenced by tattoos or piercings, for better or for worse—sort of like the ways acupuncture influences the meridians (energy channels) in Chinese medicine.
But unless a person could be absolutely sure that there would be benefits (physically, mentally, or spiritually) from either practice, it’s probably not a good idea to mistreat one’s physical or astral body in these ways.
Tattooing or piercing with the idea of decorating one’s body, making one’s self stand out as unique from all others, or whatever reasons similar reasons might be given—none of these reasons seem spiritually important, as best as I can tell. For true spiritual work and increasing our spiritual energy are best accomplished in a much more inward way. The outward, physical “trappings” are not really needed.
Having said all this, I know these practices are very popular these days. It may be just a minor fad in the major drama of passing time. But one thing that I know is true is that I have seen older people with the “remains” of tattoos on their bodies and it is not a pretty sight to see! And who knows what effects the chemicals in the dyes have had? For that reason, I would say tattoos and piercings should be avoided as a violation of our sacred body temples.
Keeping the physical body pure, clean, healthy in every way you can is surely the wisest course to take.