You don’t necessarily need CON for any content in the game, but it is very useful for Velcoffer and higher staged challenge modes depending on how well upgraded your armor is.
Masinios Staff at +11 will have 488 more MATK just from the base stats, but it provides 628 MATK compared to Regard Horn’s 257 with INT/MAMP, so you’ll be gaining another 371 there for a total of 859. Add in two more gems (let’s assume level 7s) and that’s another 288 for a total of 1147 more MATK.
The only better staff right now is Velcoffer which sounds a bit out of your reach at the moment, or a 380 weapon, which is coming with rank 10 sometime in the nearish future. Some people will suggest a +16 Primus as those are relatively affordable lately (like the guy right above me), but those only have 562 MATK over a +11, which is actually less than you gain with the powerful stats on a Masinios Staff. If the +16 rolled very good INT stats etc, then it could be better, but that will only raise the price; and it won’t really be that much better in damage, you just might get CON or other miscellaneous stats.
Any amount of ATK gain makes a large difference, especially when it’s that much. You won’t be able to break down your Regard Horn Staff for Blessed Gems, as that feature was removed, so it will all depend on whether or not you can afford to trans10 the new staff and how much budget you have. You have the option of selling your current staff if it still has potential to try to get silver to afford your Masinios, but I wouldn’t expect to get too much for a Regard Horn, even if it is trans10. I think it’s a worthwhile upgrade, but it will depend on you to decide if the cost is worth it, depending on how much silver you have and how much you can typically generate.
Your alternative options are:
• Try to hold out for a Velcoffer Staff if you can get a group together to start running that content and can afford to reroll cubes.
• Wait for a 380 weapon that you can hopefully get to +16. The Masinios Staff may still be better than a +11 380 weapon due to how good the stats on Masinios are, but I don’t have the numbers in front of me.
• Buy a weapon someone else already made trans’d or upgraded well. Lots of people are currently selling equipment that is already refined/transed, and sometimes this is much cheaper than doing it yourself.
I hope that this helps, but feel free to ask more questions if you have any.