what would be the best tool for garden edgers?

Answer 1

if you are talking about edging around the garden a spade will do or you can use a weed whacker be sure to use eye protection if you use the weed whacker.

Answer 2

The best 'tool' is Roundup. Spray it on the grass or weeds you want dead and they will be killed right down to the roots. It takes a week or so for the killing to take effect. I have used Roundup for about 15 years to trim around gardens.

PS: be sure to only spray what you want dead and do not spray when the wind is blowing at all!