Bench, angle or a file jig to regrind?

[brasileiro]

Hello. I'm looking for a new tool. I'm thinking about it for long time and I can't be sure which one is best for regrind.
A angle grinder jig or a bench grinder jig.

I'm not a knife maker and don't work on it. It's just to make the back bevel thinner on some old blades.
I have both grinders but it's not easy find the right materials to build them where I live and I don't want to fail.

Have had anyone experiences with both or one of them?

A angle grinder allow you to see the bevel while working on it but the weight and the speed may ruin a blade.

A benchgrinder don't allow you to see the bevel while working on it but allow you to use only the blade weight.
Here are 2 examples of what I'm talking about:

Bench grinder jig

Angle grinder jig

Or even a file jig

Thanks.