The campaign I am in, the DM is allowing a Homebrew item of having a blade on 1 edge/rim of the shield.

Except...

The customization tools on this website wont allow me to create the item...

Everytime I have to tell it what type of item it is, no option allows for both armor and weapons stats...

The homebrew tools are the same tools used by staff to input the stuff from the books, so if there is no item from any book that does Thing X, where Thing X is something weird and not just, say +5 to AC instead of +3, then chances of there being tools to make Thing X with homebrew are miniscule. Your best bet is to make a weapon and manually adjust your AC.

You can create a homebrew using the weapon stats and add a modifier for "Bonus" "Armor Class", this will effectively give you the weapon attack action and increase your AC by the desired amount when wielding it. 

Quote from DrakAlGhul >>

You can create a homebrew using the weapon stats and add a modifier for "Bonus" "Armor Class", this will effectively give you the weapon attack action and increase your AC by the desired amount when wielding it. 

 
I was just about to suggest this myself when I saw someone already had. Just pick whatever has the correct damage die (for a d4 I would use a sickle, for a d6 a scimitar perhaps), and then modify it.

To add the shield bonus to AC:

• Modifier: Bonus->Subtype: Armor Class->Fixed Value: 2

To get rid of the stuff you might not need (like the light and/or light properties), you would need this:

• Modifier: Ignore Weapon Property->Subtype: [property name]

If you need to add any weapon properties (like heavy for example), you would need this:

• Modifier: Weapon Property->Subtype: [property name]

If you need to the damage type, you would need this:

• Modifier: Replace Damage Type->Subtype: [new type]

I hope that helps.

PS- Don’t forget that a shield weighs 6 lbs. If you’re adding a half a dagger’s mass to it then you’re at 6.5, half of a shortsword’s would bring it to 7 lbs.