deaden, blunt

make less lively, intense, or vigorous; impair in vigor, force, activity, or sensation; "Terror blunted her feelings"; "deaden a sound"

• obtund — reduce the edge or violence of
• petrify — cause to become stone-like or stiff or dazed and stunned
• dampen, damp, soften, weaken, break — lessen in force or effect

• change, alter — cause to change; make different; cause a transformation