This was the hardest part to obtain as a 31 necro on the time-locked progression server. I made 3 short efforts (5 chief kills in total) to get the knife drop.
With a 24 wiz partner, the camp was broken with relative ease. Solo, this was not possible as slow regen meant downtime > respawn rate.
So my solo strat was to sacrifice the pet on the chief and burn him down, then feign while letting the adds leave. I was pulling from up on the ridge, which can bring tons of adds from below if not careful.
Due to breaking the camp, the easier /con goblins had respawned with some dark blue shamans... this complicated things as they heal everything around them. Ultimately the shamans cost me a death (dotted heavily) but I was able to loot the knife before the dark end.
If doing this oldschool, you might want help if attempting under level 35.
Anyone geared-up post TSS probably can resist everything they cast and skinspike potion the whole island dead on a cast of temperance around level 25-30. Runners do bring lots of help though.