A plugin doesn't need to set sv_cheats to 1 to dispatch spawnflags value.
Also, this is OP. Sorry if I am being rude, but it looks like you just learned some commands and immediately made this post.

1) overpowered
2) downpowered
3) (de)buffed candy cane

bind 0 slot10

Well played ;)

cl_allowdownload 1

Nah, 'unbind 0' willn't help.
Use 'bind 0 slot10'

I removed my previous post.

No. You should put them to the 'tf' directory, not the 'customweapons' directory.
(like this: 'Team Fortress 2 Dedicated Server/tf/models/weapons/c_models/pizda/pizda.mdl')

it's relative to 'tf' folder. example:

doesn't matter if it's a custom (downloaded) model or a built-in one.

The problem is in your custom weapons.