Stick with the plain H. don’t mess with the swords, but possibly have it be the two colors (blue and green).
Can you pipe a fairly straight line and a “shell border”? If yes to these then I recommend the following:
Then whip up a double batch of royal icing. Tint the entire batch the dark green. Load a pastry bag with a #3 round tip (that is the Wilton tip #) and pipe the out line of the H like a block letter on the cookie. You will be flooding this with thinned out royal icing so make sure that there are no gaps. Try to keep them uniform, that is the hard part.
When you have outlined all of the cookies, thin out the remaining royal icing with water. Add the water a little at a time. The consistency you are looking for is: when the thinned icing falls back on to itself it disappears after a ten count. Don’t go too soupy, but make sure it disappears into itself at a ten count.
Load the thinned out icing into a pastry bag with no tip. Cut a small opening in the pastry bag, not much bigger than the hole in a #4 tip and use this to flood the outlined Hs. Be neat and don’t let any spill over the “dam” you created with the outline. Let these dry completely. Could take a few hours, could take overnight. It depends on the environment.
When the icing is dry, whip up another batch of royal icing and tint it blue. Load the blue icing into a pastry bag fit with a #3 round tip and pipe a small shell border around the edge of the H.
Let them dry.
Too much work? Then:
Take the stencil you were going to use for airbrushing and make a batch of royal icing (do you see a trend here?) tint the entire batch green.
Lay the stencil over the cookie and with an off set spatula spread the royal icing over the stencil, then smooth it like you would if you were icing a cake smooth. Carefully pull the stencil off the cookie, repeat.
You can still pipe a blue border around a stenciled letter.
Hope this helps.