I think the word you're looking for is Swagger.
Throwing Knife Swag would be throwing knives, throwing knife books, throwing knife targets, throwing knife sheaths, stuff like that.
Swag Definition (noun): loot - booty - spoil - prey - plunder
Verb: Walk or behave in a very confident and typically arrogant or aggressive way: "he swaggered along the corridor". Noun: A very confident and typically arrogant or aggressive gait or manner.
Yes, the throwing knife is awesome, and does take skill. Everyone loves throwing knife videos.
All of the lethals take a certain amount of skill.
C4 definitely takes a lot of skill, and is probably the most rewarding. You can plant it discretely and detonate from afar, or toss it over obstacles to get pesky hiders. Jump throwing C4 is definitely a skill. You need a lot of coordination to execute and get the right flight.
I would say claymore takes a lot of skill. It's hard to place claymores such that the laser cannot be seen and such that if the person is running by that they'll actually be killed by it. When used correctly it can be great though.
Frags and semtex are a little different. Frags can randomly bounce and give you lucky kills. I would say cooking a frag is skillful though.
TK definitely though. Obviously you need a lot of skill.
I would say betty takes the least skill. You just plop it down. Obviously you can put it in unobvious places, but that's just about it.