I think the word "tactical" is incredibly overused in the firearms industry. The word is more of a marketing ploy than anything else. Stick the word "tactical" on a gun, and folks want the product even more. To me, "tactical" is the way the gun is employed rather than any specific features. In the hands of someone who know how to use it, a S&W Mod 66 is more "tactical" than a HK Mk 23 in the hands of someone who does not know how to employ it, IMHO.
Tactical: any maneuvers for gaining advantage or success.
Using the definition, if you are trying to drive a nail in a 2x4, using a hammer could be described as "tactical". There are "tactical" knives that don't have a light rail or whatever. It seems that when they add the word "tactical" to any product, it turns it into "tacticool" and makes it more desireable and therefore, more sellable to the "Mall Ninja's" and "Internet Commando's".