Dear everyone: if you didn't catch what Eliza Creststeel said, go back and re-read it. And read it again. And again.
(Note: you can kill Darkheart in about 15 seconds, but get very little rep when you do fast kills.)
Defeat 4 raiders in ~35 seconds for 85-173 rep each, once or twice per minute in catacombs.
Defeat 1 Darkheart in 50-180 seconds for 115 rep, once every minute or two.
Defeat 1 Remington in 90-300 seconds for 115 rep, once every few minutes.
Defeat 1 stump boss in 70-240 seconds for 115 rep, once every couple minutes.
(The difference is less dramatic with multiple weapons, but any-which-way you do it, bosses are a waste of time. They guarantee you get lower rep per minute.)
When your notoriety is 42 or higher, you have to move from catacombs to cursed caverns. But below notoriety 42, catacombs is the only place to be, for fast weapon grinding. Enemies in cursed caverns tend to take too much longer to defeat, when you are below notoriety 42.
And finally, check out the
Reputation Chart and Guide.