There aren't any universal meanings for tattoo symbols. Check out tattoo symbolism here: http://tattoo.about.com/cs/beginners/a/symbols_intro.htm But remember, sometimes a rose is just a rose. It doesn't mean or symbolize anything!
A symbol that depicts the sign of courage in a tattoo is a koi fish, a skull and the lion. As with all tattoos the colors have a lot to play in the meaning as well as the direction the tattoo is facing or going.
A dagger and dragon tattoo can symbolize several different things. It can symbolize courage, strength, or perseverance for example. Tattoos are very personal, and each person has their own beliefs as to what their specific tattoo symbolizes.