The idea is this:

1. Have two guns, but don't pick up the Rapid Fire upgrade.

2. When Wigwam jumps at the start of the fight, estimate where he's about to hang in mid-air and move in that direction. Jump if his hanging position is above the horizon line.

3. Shoot Wigwam in mid-air exactly TWICE (he is guaranteed to block any subsequent shots). Start shooting just before he stops in mid-air to prevent him from blocking the first shot.

4. When he starts jumping down, look where he's about to land and stand in the EXACT same spot.

5. Shoot down any daggers coming your way.

6. Just before Wigwam lands, jump vertically upwards and shoot downwards. Mash both Fire buttons to increase the mashing speed.

You will kill Wigwam in one jump.