Sorry but Serena Williams has a very weak brand as there are 2 qualifiers for a strong brand -
1) Is it (almost) the only choice. For example, if you want an Apple and the shop has sold out but has a Microsoft PC on offer, would you buy, or not? Apple = very strong brand, MS = weak brand although a very well known one. Is a Serena Williams product the only option to many? Nope.
2) Do you advertise the brand to your friends? Take Apple as another good example. How many Apple products have people who own an Apple product sold to their friends 'check this out, it's great'. How many Microsoft products have Microsoft owners sold to their friends 'hey, check Windows 10 out, you have to get it'. And how many Serena Williams products have owners sold to their friends?
The word 'brand' is such a cliché these days and few understand the concept of what a strong brand really is. They get confused with a well known brand, which anyone with enough money can create, over a strong brand which is a lot harder to create.
These are strong brands -
Head & Shoulders
Red Bull
Ferrari
Mitsubishi Uniball pens
Apple
Tropicana Juice
Kanger electronic cigs
Amazon
Google search engine
Jonny Walker Black
Rolex
In-Out-Burger
That great local coffee/sandwich shop on the corner that only has one branch
I'm sure there are more than a few tool makers that are very strong, not familiar with tool though
These are weak but well known brands
Coke
Pepsi
Most of the big super market chains
GM
Dell
Microsoft
All governments
McDonalds
Starbucks
So never confuse a well known brand with a strong brand.