English to Spanish Law/Patents Ships, Sailing, Maritime

Although it commonly happens that in rescuing property from danger the salvors necessarily expose themselves to peril, yet work involving no extraordinary exertion, enterprise, or risk may constitute a salvage service; but where risk is incurred by the salvors, that circumstance is most material with reference to the question of the amount of the reward.

Entiendo sin problemas la primera frase, pero el fragmento seleccionado me impide comprender la segunda. ¿Alquien puede explicarme qué es lo que significa? Muchas gracias!