H.E.A.V.E.N. -A, -B and -C
Defeat Gryphus in level 8. Then, re-enter Primordium (level 0) after the intermission sequence and enter the door behind you.
Keep weapons
When you die and lose your weopans, go back to where died. However, this time go with nothing. When you pick up your weapons and die, you will have them on your "transport".
H.E.A.V.E.N. -A, -B and -C...