Anyone recommend a sander for render?

[whatxd]

My house is smooth sand and cement render which i did last year. There's one panel where on the day, the sun came out and was baking away longer than forecast. Consequently, it went off in no time so we didn't get the time on it that you'd ideally want.

Whilst in dull/direct light it looks fine, with the sun shining across it, or when my exterior lights are on, i want it better.

Can anyone recommend a sander and appropriate discs that could get it better?

[bennno]

Angle grinder with masonry grinding disks, or a silicon carbide rubbing block.

[whatxd]

Thanks, I'd never heard of that particular rubbing block before, just ordered one and will give it a go