From what I can tell it is possible but super improbable to get both rolls exactly how you need it.
Not sure if it needs to be higher than copper hammer, possibly need to be.
I saw a video of someone who wanted a 70 hit lighting bokuto with poison damage. It took him literally days and hundreds and hundreds of attempts.
For example, you may try hundreds of times and get some unusable combo like 70 hit cold with fire elemental damage.
Your best bet is to get the 70 hit area you want and then enhance it to get 40-50% of it to be elemental.
I made a reptile slayer axe with 70 hit energy and enhanced with Agapite so half of the damage is energy/cold