What do you mean by weak then?
Much of the charm of higher quality teas come from the subtleties in the flavors, they won't ever be overpowering. They can taste muted with age or improper dosing/brewing. And using too much tea and/or oversteeping will make the flavor profile saturated/flat, rather than be overpowering.
If you're looking for a clear, piercing flavor to "slap you in the face", you'll probably want something with a lot of aromatics, like a smoky Lapsang, a reinforced Earl Grey or other flavored blend, maybe a Gunpowder with it's bitterness, or even Matcha. In the herbals section, Hibiscus and many Rooibos blends might have something of what you're looking for.
And you might want to pair it with flavor enhancers like sugar and milk/cream depending on flavor profile.
A Lapsang sweet tea, or a Matcha Latte might do the trick for you.