Use 'attenuate' when something is intentionally made less strong, not when it weakens on its own. Soundproofing materials are used to attenuate noise in recording studios.
Pro Tip 2/3
Not Eliminate
'Attenuate' implies reduction, not complete removal. Something still remains after attenuation. The curtains will attenuate the sunlight, but not block it completely.
Pro Tip 3/3
Careful Use
Use 'attenuate' in situations where precision is needed; it's not casual language. The new policy is designed to attenuate the risks involved in online transactions.