[dupratac]

but pick a few tools that suit you well and get really good at those.

I think, even one tool is too much, if you (sometimes literally) shit your pants in an "self defense" situation.
Defusing doesn't work all the time, either.
To be able to defend yourself with above average odds, I think it takes daily practice and constant exposure to dangerous situations (police, security, army - each in their own field - maybe professional fighting - MMA or Boxing, less the 'olympic' stuff that sticks too very restrictive rules).
Everything else - including Martial Arts and even self defense courses - is probably just some form of nice ballet - so I wouldn't say Kendo is underrated, I'd rather say many other things are overrated.