Can anyone tell me what the law is about fixed blade knives being concealed in NH? I'd like to carry a larger fixed blade IWB, but im not entirely sure of the legalities of it. Everywhere I look seems to be a dead end. Say I wanted to conceal a 7 inch bowie IWB, would that be legal?

159:16 Carrying or Selling Weapons. – Whoever, except as provided by the laws of this state, sells, has in his possession with intent to sell, or carries on his person any stiletto, switch knife, blackjack, dagger, dirk-knife, slung shot or metallic knuckles shall be guilty of a misdemeanor; and such weapon or articles so carried by him shall be confiscated to the use of the state.

Section 159:19-a
   159:19-a Criminal Use of Pistol Cane or Sword Cane. –
   I. Any person who uses a pistol cane or sword cane on another person with intent to commit a crime punishable as a misdemeanor shall be guilty of a misdemeanor.
   II. Any person who uses a pistol cane or sword cane on another person with intent to commit a crime punishable as a felony shall be guilty of a class B felony.
   III. Neither the whole nor any part of a sentence of imprisonment imposed for a violation of this section shall be served concurrently with any other term of imprisonment.

Section 159:24
   159:24 Sale of Martial Arts Weapons. –
   I. ""Martial arts weapon'' means any kind of sword, knife, spear, throwing star, throwing dart, or nunchaku or any other object designed for use in the martial arts which is capable of being used as a lethal or dangerous weapon.
   II. Any person who shall sell, deliver, or otherwise transfer any martial arts weapon to a person under the age of 18 without first obtaining the written consent of such person's parent or guardian shall be guilty of a misdemeanor.
   III. Paragraph II shall not apply to fathers, mothers, guardians, administrators or executors who give a martial arts weapon to their children or wards or to heirs to an estate.
Source. 1986, 222:3, eff. Jan. 1, 1987.

So i'm fine carrying something like one of the bottom two here?

me likey, you will have no problem carrying one of those.

Lots of self defense stores here sell knives listed above with no problems, I have seen many Butterfly knives, daggers, throwing stars, sling shots, blow guns, tazers, black jacks, cane swords and other Evil looking knives for sale right out in the open. Just check hampton beach, It is suprising the stuff they have in those cases. Its mostly chinese junkyard imports but still very illegal in states other than NH.

Being able to buy them, and concealing them are entirely two different things though.

IMO you should be good to go.  I think the legal definition of dagger is "double-edged"  same thing with dirk.
ETA: is the top sharped on the smallest blade?

Those aren't mine, I got them google image searching Busse.  I'm buying one of these I think.

http://www.bussecombat.com/knives/index.shtml

This is what I carry.  It's a good size, and its not scary looking at all.