Historical minis will either come with an open hand of sorts to drop the spear in or will require you to drill out a hole for the hand.
You will need a pin vice of some sort, and I recommend a bit slightly bigger then the shaft of the spear/axe/whatever.
I strongly recommend one with a free spinning end to it. I have multiple pin vices, and one has a bit retainer at both end. It is murder on the hand to use it.
https://www.walmart.com/ip/11Pcs-Precision-Pin-Vise-Mini-Micro-Hand-Twist-Drill-Bits-Set-Rotary-Tools-Kit/846321400?wmlspartner=wlpa&selectedSellerId=2961&adid=22222222227248868411&wl0=&wl1=g&wl2=c&wl3=293192242062&wl4=pla-510219584589&wl5=9052441&wl6=&wl7=&wl8=&wl9=pla&wl10=113509951&wl11=online&wl12=846321400&wl13=&veh=sem&gclid=Cj0KCQiAg_HhBRDNARIsAGHLV51VlPPl0bsLHQSetZRj65DXwE7j1aEaVFf3cQ66kgu9RlPJJoJLg0AaAvlHEALw_wcB
https://www.hobbylobby.com/Crafts-Hobbies/Model-Kits/Paint-Brushes/Pin-Vise-with-Drill-Bits/p/1225?gclid=Cj0KCQiAg_HhBRDNARIsAGHLV501zSgLbFbQAWlRUvUudnfpdkOeT8XJJ6s1s4qHRSl1-hvOnIjApAkaAnHZEALw_wcB
If you need them, here is a tutorial from Footsore:
https://www.youtube.com/watch?v=wheeAzA1ShY
Lastly, I strongly recommend brass rod for spears/pikes over plastic or even pewter ones. They are much harder to break and will last much longer. You can buy these from people like Footsore or North Star, or you can very easily make your own with brass rod from a model store. In fact, the banner man in my photo originally had a resin shafted flag. I cut the resin haft off, drilled out the flag, and replaced it with a brass rod. The flag will now break long before the rod does.
Some home made brass spears for some saxons (cut with a pair of dykes and a point formed with a dremel tool):