Thermobaric grenades

Yes i know, there is another idea about thermobaric grenades but this one is very different.
In the other thread it would deal damage, meaning that you can kill a player with it and yet it's a tactical.
Now to my idea. It would hardly take any coding at all since it's already implemented in vanilla minecraft. Weakness potions. All that would need to be changed is that they would have to increase the range and splash radius similar to the grenade.
You would get 2 every life and it would be a tactical with a very large radius. (Maybe twice as big as the grenade?) It would not deal any damage to the player, but it would make them weaker so your guns and sword deals extra damage under the duration of the weakness effect, and it would cost 5 dollars.
Pros:
Useful in every gamemode, except for zombies in infect.
Large radius.
Useful if you are running low on ammo and you need to get kills with less bullets.
Easy to code.
Does not replace your lethals since it's a tactical.
Makes rushing easier.

Cons:
Can't kill enemies.
Expensive.
Short duration time?
Can accidentally give yourself weakness.

If you think that this is a good idea, then please also suggest how long the effect would last. I think that 3 seconds would be balanced.

 

No it would not do anythig to them, but all enemies get increased damage on them.

As i said they would deal 0 hearts.