It seems to be not quite balanced yet. A bronze-clad platinum-hammer wielder wins almost every time against steel armored dwarves, no matter what weapons they have (except slade hammers, which are even better, of course). Every blow seems to break bone, even through the armor.
Why is this bad?
A platinum hammer would have considerably more force behind it than a steel hammer, assuming one was strong enough to swing it. Bronze is arguably a much better metal for armor than iron and is probably as good as steel, or so close as to make little difference. The platinum hammer, being far denser than steel, is going to shatter armor and bones quite easily.
Seems to be alright to me.
There's a few problems. More weight is not always better - there is an ideal strength:weight ratio. There's also differences in metal strengths, and bronze is not a great choice for armor.
We can look at two different kinds of strength to compare the different metals you mentioned.
Shear strength is the kind of strength that is important when deciding if your hammer's handle will break. You have shear stress when you're using your hands to push it one way, but the target's body is resisting, or the end of the hammer is very heavy and needs a lot of force to move. This is measured by the
Shear modulus. Low shear strength would mean the handle breaks, or is a bit wobbly, like it's made of rubber.
Compression strength is the kind of strength that is important when your hammer's head strikes your enemy's armor. There will be a lot of force in the impact, and the head of the hammer will be compressed. If it has high compression strength, it will do a lot of damage because it will not yield on impact - it will simply smash through what it hits. If it has low compression strength, it would be like a wet towel - no matter how fast you swing it, it's going to be soft when it hits, so it will transfer all of its impact energy slowly, causing less damage. Compression strength is measured by the
Bulk modulus.
While a rubber stick with a wet towel on the end of it might be loads of fun for smacking people, it's not likely to kill anyone no matter how heavy the towel is, so you want as much shear strength and compression strength as possible.
Let's compare the shear strength, compression strength, and density of platinum, bronze, and steel.
Metal, | Shear strength, | Compression strength, | Density |
Platinum | 61 GPa | 230 GPa | 21.5 g·cm−3 |
Bronze | 44.8 GPa | 112 GPa | 8.96 g·cm−3 |
Cast steel | 78 GPa | 139 GPa | 7.8 g·cm−3 |
Reference for shear strength.Reference for compression strength.So, we can see that platinum is awesome for hammer heads - it's both incredibly dense and has enormous compression strength. Steel is clearly better than bronze, but it's a bit light. It happens to have better shear strength than platinum, however, so it might make for a nice handle, since it's both lighter and stronger in that role.
For armor, bronze is a bad choice because its shear strength is only 57% of steel's shear strength. To make matters worse, bronze armor would be denser, so you'd either have to use thinner armor to make it comfortable, or make the armor nearly twice as thick (and very heavy) to provide about the same protection as steel. Bronze is inferior to steel in just about every way.
Now, that's not all that's wrong with those results. I mentioned weight above, so let's look at that now.
Different weights should be ideal for different levels of strength. Clearly, an extremely dense hammer is not going to be helpful to someone who isn't very strong. Even if they could pick it up, they wouldn't be able to get it going fast enough to do any real damage. In a low-speed impact, you simply get pushed back a little bit, and maybe a bit bruised if you're not wearing any armor. In a high-speed impact, your body doesn't get the chance to move much before the damage is done. This is why a 1 lb. hammer will do more damage than a 100 lb. hammer, unless you happen to be really, really,
really strong.
A modern steel sledgehammer might weigh 15 pounds. If you make it out of platinum, either you'd need to make it very thin (and weak), or you'd need to make it very heavy, in other words, it would weigh 41 pounds instead of 15 pounds. Now, that's great if you're really strong. However, for a dwarf without any strength enhancements, 41 pounds would probably be too much, and that kind of sledgehammer would be damn slow. You could easily dodge it, and, even if it did hit you, it would do much less damage than if that same dwarf used a 15 pound sledgehammer.
Tl;DR Ideally, a dwarf would be armed with a sledgehammer with a platinum hammer-head, a steel shaft, and steel armor, and, ideally, the hammer would be made larger or smaller to fit the dwarf's strength.