Multisig
A wallet that requires several private keys (not just one) to authorize each transaction, spreading out the risk of a single point of failure.
A multisig (“multi-signature”) wallet is configured as M-of-N: it needs M valid signatures out of N possible keys to move funds — for example, a 2-of-3 setup needs any 2 of 3 keys, so losing or exposing a single key doesn’t mean losing the funds or giving an attacker control.
Multisig is one of the standard responses to exactly the kind of single-point-of-failure risk a compromised seed represents: if one key’s entropy was weak or one device was compromised, an attacker still can’t move funds alone.