When spears cast onto figures are too bendy for my tastes and likely to turn into spaghetti during play, I replace them with brass spears.  For 15mm figures, 1/32″ brass wire works nicely for spears, and .020″ brass wire for javelins.

Cut the wire to length.  Roll it under an XActo blade to score it.  Then simply bend and snap at the score.

With a hammer, tap one end of the shaft flat to make the blade.  Tap both ends flat to add a butt-spike.

Clip the flattened end(s) into a point using a small wire-cutter or sprue-snips.

File the spear tip edges to remove flashing left over from the snipping.

You don’t have to use a 100 pound baby anvil to cold forge little brass spears.  But if you happen to have one in your basement, it’s fun to use and saves you the trouble of buying a tiny crafters anvil ^,^

Depending on the figure, there are different ways to attach the spears if the figure was not already cast with an open hand.  Some figure need a small hole drilled through the hand to slide the spear into.  For this, a small pin-vice does the trick — a hand held hobby drill that you just spin between you fingers.  Then slide the spear into the hole and glue in place.

Many times, I just use an XActo knife to carve a trough in the hand.  Glue the spear in the trough.  Also if possible, glue the bottom of the spear to the base, or some portion of the shaft to part of the figure holding it.  With 2 glued anchor points, it is far less likely to break loose during play.  If the metal alloy of the figure is soft enough, the open fingers can be squeezed with tweezers for a snug fit around the spear.  And the fingers gripping around the spear can be added with a tiny dab of putty.

For some figures, I leave the original spear tip in place on the figure and only replace the rear portion of the spear shaft.  For this technique, cut off the unwanted portion of the spear shaft, mark the center point to drill with the tip of an XActo, then carefully drill a short hole lined up along the axis of the shaft.  Then cut a portion of brass wire for the rear shaft and glue it into the hole.

Old Glory Early Imperial Romans: the top left figure has a spear glued in a carved hand trough, and putty added to complete the finger grip; the center 2 figures have just the rear shaft glued into their hands, the original remains as cast on.  (The right 2 figures don’t actually have spears any more… They are other conversions from the same figures in the center — the rear spear shaft has been removed leaving a tiny nub for a sword pommel, the front shaft and spear tip have been carved into a short roman sword, the hand has been recarved for a proper grip on the position of the sword, and the shield has been carved into a fully oval one.)