So apparently the last guy's measurements were wrong. RIP. I'm gonna redo it scaling from Guts who apparently has a listed height. However I will be keeping the estimated thickness of 7 cm.
http://i.imgur.com/dOSHHV1.png
Density of Steel - 8050 kg/m^3
Guts' Height - 2.04 meters
Guts' Height 2 - 633 px
Dragonslayer Total Length - 550.18 px
Dragonslayer Width - 100.57 px
Dragonslayer Tip Length - 50 px
Dragonslayer Tip Width - 68.01 px
2.04/633 = 0.0032 meters per px
550.18-50 = 500.18 px
500.18*0.0032 = 1.601 meters
100.57*0.0032 = 0.322 meters
1.601*0.322 = 0.5155 meters^2
0.5155*0.07 = 0.0361 meters^3
0.0361*8050 = 290.61 kg
50*0.0032 = 0.16 meters
68.01*0.0032 = 0.218 meters
A = (0.15*0.204)/2 = 0.0174 meters^2
0.0174*0.07 = 0.0012 meters^3
0.0012*8050 = 9.66 kg
290.61+9.66 = 300.27 kg