Greetings friends!
Figured this out. Ran into this confusion too... because in the previous version the weapon was set up as a separate object under your list of Game Objects. I looked everywhere for it. It really threw me off that it did not exist anywhere O_O. So I started poking around the code which resulted in me learning some basic assembly. Here is what is going on...
ANSWER
In this example module, without doing any coding, your weapon must be a 8x8 pixel sprite on the first row.
By default, the vertical sword is tile 8 and the horizontal is tile 9.
You can go to Project Settings and then User Constants to change this-- but it only allows you to change the horizontal row. Look for these two....
SPR_WEAPON_V (which is the X value of where your horizontal weapon art is located.)
SPR_WEAPON_H (which is the X value of where your horizontal weapon art is located.)
DEEPER ANSWER AND CODE STUFFS
The script you add to your project to make your character attack when you press B on your controller is "b_create_melee.asm". But I was surprised that the code to show your weapon when you attack is not in the b_create_melee script at all.
To see the code that makes your weapon display, go to Scripts > Defined Scripts > Handle Sprite Pre-Draw ... this is where it looks at which direction you are facing and then draws the weapon on top of your character with the "DrawSprite Width, height, X, Y, Offset" function.
Also, you will want to look in Scripts > Defined Scripts > Handle Sprite Weapon ... this is where it does the collision detection. The width of your weapon is hard coded at 8 pixels in there.
Editing this to work like the old version, which allowed you to have a game object which could be animated and all the other fun features is currently beyond my skill level. I literally learned how to read the assembly code tonight to understand. It is possible that I am mistaken and it is still possible to build a custom melee weapon into the first slot like in the previous Adventure Module. If so, please let me know.
For the game I am making, my hero wields a 16x16 battle axe with a motion trail. So I was trying to figure out how to get it to display and animate properly when he attacks and do the proper hit box. The 8 sprites per row limit on the NES has been killing me X_X. If anyone has a sprite drawer example, or large size weapon script-- I would be very grateful for any help you can give.
Battle on!
Artix