Will Lockhart was really a peripheral character.
SPOILERS
The main story involved the ranch owner Alec Waggoman, his dangerous son Dave and his loyal main ranch hand Vic Hansbro. You could take Will Lockhart out of the film and it wouldn't have mattered. In fact it would probably have made the film better because the time wasted on Will Lockhart could have been used to focus on the characters critical to the story.
Vic Hansbro should have been the main character and the film should have been seen through his eyes. He is a tragic figure really. Alec Waggoman ensured his loyalty by promising him a stake in the ranch and cynically used Vic as a minder for his son Dangerous Dave. But Vic thought Alec was being sincere and so his loyalty was freely given. He looked up to Alec as the father he never had.
Vic was very wrong to have been involved in selling repeating rifles to the Apache but it was Dave's idea and he was the driving force behind it. Vic was willing to do it while it was only a small number of rifles but when Dave bought a few hundred Vic objected, they fought and Vic killed him. But in the end Vic was blamed as though it had all been his idea. But apart from that one thing he was basically a good man and his fate was a tragic one.