Ok. First off, I have no idea how easy it is to get wood, paint, and tools in Singapore. I imagine it is just as easy as it is here, but I've only been there once, and I wasn't shopping for cosplay supplies
The shaft of the spear is the easiest part. Just get a dowel rod of the length you want. You should be able to get pre-cut round dowels (shafts) at any store that sells wood.
Pick the side that will have the spear point and make a mark that is between 3 and 4cm longer than the shank of the spear (the shank is that rounded piece between the blade and the shaft). Lay the shaft in a door frame or a long straight edge, and hold your pen or maker at the point you made. Rotate the shaft, and draw as straight a line as you can. Once you're done, that should give you a ring all the way around. Sand the wood above this ring about 1.5 - 2cm, so that you have a smaller round bit sticking out of the end of your shaft. Cut a notch in the center of the shaft, about 1.5 cm wide, this will help when you go to attach your spear head.
For the head itself, I'd get a sheet of plywood, and copy the design in the picture. Cut the design out (or have it cut, I don't know how good you are with wood) and sand the entire piece in to shape with very rough sand paper (something like 60 grit). Keep sanding with lighter and lighter sand paper until you have a smooth finish with as little wood grain as possible.
For the shank I'd look for some plumbing fixtures that are the right shape and size. If you can't find anything, you could try and sculpt that piece out of clay. I don't know how well you can sculpt, but it would be pretty simple to get that shape. Just make sure that if you do sculpt it, you make the inside large enough to go over the sanded down part of your spear shaft.
Once you get all of your pieces together, I'd do a test fit, slide the shank piece over the shaft, and then place the head in the notch you cut out earlier. If things don't fit together like you want then to, then sand until they do.
After you get the fit you want, make a final finishing pass with the sand paper over all of your parts. You'll want to use a very fine grit (400 - 600) and make sure you get all the sawdust off your pieces. Spray on a light coat of primer, sand it lightly, and spray on another light coat. Sand this coat lightly, then spray on a light coat of whatever color you are going to use. For the spear head and shank, I'd use a chrome or silver paint. I don't know what color the spear shaft is in the game, but I'd guess it was laqured red or black. If you do use chrome spray paint, it should only take two or three light coats to make it look like metal. Don't sand in between the coats of the chrome paint like you did with the primer.
When the paint dries, its time to stick all the parts together. An epoxy glue would be best. Just don't use too much, or it will get messy very fast. You can use the 5 minute fast cure, but the 30 minute cure will be much stronger.
That should do it for the spear. Just add the decorations and details you want, and its ready. Let me know if you have any questions.
I'll talk about the shield in the next post.
I need to make some visual aids, so the shield post will be delayed a bit.