Strength relics are at the most a stop-gap relic while leveling and are outclassed by every other relic at level 72 and in the OP levels. Once you hit level 72 and start getting better equipment there is no practical reason to equip a strength relic.
The only time I have used one at level 72 is on Maya with a Grog Nozzle with a specific build geared towards trolling Pete the Pushover by making the fireman reject kill himself.