This list has no method of dealing with armor over 12 other than your Farseer. It would be better to take a lance walker.
If you want to stick to the overall theme of your list, you could swap the warwalkers for vyper jetbikes.
Jetbikes are best taken in multiples of 3 for the cannons.
If you want to keep the warwalkers, keep them in one squad. This will allow the farseer to buff them both with prescience or guide. It will also make them less likely to give out first blood.
'Bike' Themed List with Vypers
WarWalker list