translucent materials get darker the thicker it gets, because light cant penetrate as far due to impurities etc. so it would be darker towards the bottom instead of the top.
Also there might be caustics in the bottom dark area from light reflecting from the floor.
the highlights doesnt describe the form very well. It looks like a fairly flat oval, but i assume you're going for more of an egg shape. Consider the form when placing the highlights.
The bottom highlight is too bright and implicates another lightsource from below
alas, without background its hard to tell whats going on, but if you want translucency, you need something behind it to give it some context. it sells the illusion better.
good work so far 

Hey hank, at last i came around to reply.
Great to see you working on your own stuff! Love the painterly style. Definitely looking forward to see it in action.
but... BUT... dat blue highlight on the tree. i cant stop staring 

Great work man, and godspeed!

Just as a heads up how much colors can help the piece.

Rocks are grey, yes, but not just grey. every material is lit by the according environment they're in. a blue sky tends to give everything a blue tint. Obviously this is exaggerated, but it might help you get some ideas.
play around with it. dont pick the obvious colors.

have fun

This is mostly nerdy reply about the actual attack you chose. Apply as desired.

There are several things catching my attention with this attack:
-it is using the spear one-handed
-it is starting from an idle/relaxed hold moving instantly into the thrust.
-there is a twisting motion, as well as a thrusting motion.
-he has a shield but he doesnt use it.

Lets examine this a bit further:
-using a spear onehanded has several disadvantages, especially in a thrusting attack. you cannot accurately thrust at a specific point, which is kinda the idea with a spear. your only method of adjusting the final location of the tip is the twist of the wrist. Due to the length of the spear and the resulting leverage it will result in very a inaccurate and also weak attack.

-the initial twisting/turning of the spear in 90degrees just amplifies the problems mentioned above. you will hit even less reliably, and the twisting motion will reduce the thrusting power. your attacking direction is forward but the spear tip's momentum is going downwards, and with the lack of control from using only one hand you'll end up with a really bad thrust.

now considering these points, one possible thrusting motion could be: his shield arm grabs the middle of the spear (right above the right hand's position) grips it tight and thrusts it forward while the right hand slides back controlling the direction of the spear.
This will also make him utilize his shield, so that he's blocking attacks from the front while preparing and executing the attack(i.e. grabbing his spear).
Weak explanation but i hope you get the idea.
The reasoning behind this is
-utilizing the whole length/range of the spear.
-strengthening the thrust by fixating it in the middle of the pole.
-controlling it at the far end for pinpoint attacks or quick motion adjustments

i couldnt resist