If your tattoos are a symbol of identity, it's likely you feel something in your life right now is robbing you of your self-expression.

The best analyst of your dreams is always you, but here are some rough symbolisms I picked up:
+ the knife being pressed into your skin seems like a violation, and a violent one (you're being cut, even though it's slow-moving; maybe you feel it's a subtle/gradual disruption?). The knife itself represents the intruding force.
+ the ink drains out... something like a sapping or draining of your reserves, whether of power or identity or what depends on what your tattoo means to you.

Some things you might want to look at are who or what is holding the knife. Is the cut self-inflicted and you don't realize it? If so, you feel like something you're doing is self-destructive. Is it an authority figure or boss? And so on. Of course, me framing the question now means you'll be predisposed to dream it's either you or your boss in perhaps another 2 days, so I've probably fouled things up. Definitely a good argument for getting lucid is that you're more aware of things in your dreams and can actually analyse them realtime.

Wow. That actually makes a whole load of sense, in light of some personal improvement projects I'm undertaking that coincide with the start of these dreams. So thanks for the insight.

Not a problem. The offshoot of having a research background in lucid dreaming is that you can do fun party tricks like analyzing dreams pretty well, even for complete strangers (I also read tarot cards). Lucidity is great for acquiring self-knowledge. If you want to learn more about lucid dreaming, you can check out my mefi posting history and livejournal memories and just start following links.

Too bad for the world I'm going into research and not therapy, because I got skills.